NCERT Solutions for Class 9 Science Chapter 10 Gravitation

NCERT Solutions for Class 9 Science Chapter 10 Gravitation

These Solutions are part of NCERT Solutions for Class 9 Science. Here we have given NCERT Solutions for Class 9 Science Chapter 10 Gravitation. LearnInsta.com provides you the Free PDF download of NCERT Solutions for Class 9 Science (Physics) Chapter 10 – Gravitation solved by Expert Teachers as per NCERT (CBSE) Book guidelines. All Chapter 10 – Gravitation Exercise Questions with Solutions to help you to revise complete Syllabus and Score More marks.

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NCERT TEXT BOOK QUESTIONS

IN TEXT QUESTIONS

Question 1.
State the universal law of gravitation. (CBSE Sample Paper, CBSE 2010, 2011, 2012, 2013, 2015)
Answer:
The force of attraction between two particles or objects is

  1. directly proportional to the product of the masses of the objects and
  2. inversely proportional to the square of the distance between them.

Question 2.
Write the formula to find the magnitude of the gravitational force between the earth and an object on
the surface of the earth. (CBSE 2011, 2012, 2013)
Answer:
NCERT Solutions for Class 9 Science Chapter 10 Gravitation image - 1
where M = mass of the earth, m = mass of the object, R = radius of the earth.

Question 3.
What do you mean by free fall ?

Or

What is meant by free fall ? (CBSE 2010, 2011, 2012, 2013)
Answer:
When an object falls towards the earth under the influence of gravitational force alone, then the object is in free fall.

Question 4.
What do you mean by acceleration due to gravity ? (CBSE 2011, 2012, 2013)
Answer:
The acceleration with which an object falls freely towards the earth is known as acceleration due to gravity. It is denoted by ‘g’.

Question 5.
What is the difference between the mass of an object and its weight ?
(CBSE 2010, 2011, 2012, 2013)
Answer:

MassWeight
The quantity of matter contained in a body is called the mass of the body.The force with which the earth attracts a body towards its centre is called the weight of the body.
Mass of a body remains constant.Weight of a body changes from place to place as it depends on the value ‘g’ and ‘g’ is different at different places.
Mass of a body is never zero.Weight of a body at the centre of the earth is zero.
Mass is a scalar quantity.Weight is a vector quantity.
Mass is measured in kg.Weight is measured in kg wt or N.
Mass is measured by a beam balance.Weight is measured by a weighing machine or a spring balance.

Question 6.
Why is the weight of an object on the moon 1/6 th its weight on the earth ?
Answer:
NCERT Solutions for Class 9 Science Chapter 10 Gravitation image - 2

Question 7.
You find your mass to be 42 kg on a weighing machine. Is your mass more or less than 42 kg ?
Answer:
Weighing machine gives the weight of an object.
Weight = Mass x g
NCERT Solutions for Class 9 Science Chapter 10 Gravitation image - 3
Thus, mass is less than the weight.

NCERT CHAPTER END EXERCISE

Question 1.
How does the force of gravitation between two objects change when the distance between them is reduced to half ? (CBSE 2011)
Answer:
NCERT Solutions for Class 9 Science Chapter 10 Gravitation image - 4
Thus, the force of gravitation becomes 4 times its original value.

Question 2.
Gravitational force acts on all objects in proportion to their masses. Why, then, a heavy object does not fall faster than a light object ? (CBSE 2015)
Answer:
The acceleration with which a body falls towards the earth is constant (= 9.8 m s-2) and independent of the mass of the body. Thus, all bodies fall with the same acceleration irrespective of their masses. That is why, a heavy body does not fall faster than the light body.

Question 3.
What is the magnitude of the gravitational force between the earth and a 1 kg object on its surface ?Mass of the earth is 6 x 1024 kg and radius of earth is 6.4 x 106 m.
Answer:
NCERT Solutions for Class 9 Science Chapter 10 Gravitation image - 5

Question 4.
The earth and the moon are attracted to each other by gravitational force. Does the earth attract the moon with a force that is greater or smaller or the same as the force with which the moon attracts the earth ? Why ?
Answer:
Gravitational force with which a body A attracts another body B is equal in magnitude and opposite in direction to the gravitational force with which a body B attracts the body A. Thus, the magnitude of force with which the earth attracts the moon is equal to the magnitude of the force with which the moon attracts the earth. Thus, both the earth and the moon attract each other with equal forces.

Question 5.
If the moon attracts the earth, why does the earth not move towards the moon ?
(CBSE 2011, 2013, 2015)
Answer:.
The acceleration produced in the earth due to the force exerted on it by the moon is very small as the mass of the earth is very large. Hence, the movement of the earth towards the moon is not noticed.

Question 6.
What happens to the force between two objects, if

  1. the mass of one object is doubled ?
  2. the distance between the objects is doubled and tripled ?
  3. the masses of both the objects are doubled ? (CBSE 2011, 2013, 2014)

Answer:
NCERT Solutions for Class 9 Science Chapter 10 Gravitation image - 6

  1. F is doubled if m1 or m2 is doubled.
  2. F becomes 1/4 times the original value if distance (r) is doubled and F becomes 1/9 times the original value if r is tripled.
  3. F becomes four times the original value if both m1 and m2 are doubled.

Question 7.
What is the importance of universal law of gravitation ?
Answer:
The gravitational force plays an important role in nature

  1. All the planets revolve around the sun due to the gravitational force between the sun and the planets. The force required by a planet to move around the sun in elliptical path (known as centripetal force) is provided by the gravitational force of attraction between the planet and the sun. Thus, gravitational force is responsible for the existence of the solar system.
  2. Tides in oceans are formed due to the gravitational force between the moon and the water in oceans.
  3. Gravitational force between a planet and its satellite (i.e., moon) decides whether a planet has a moon or not. Since the gravitational force of the planets like mercury and venus is very small, therefore, these planets do not have any satellite or moon.
  4. Artificial and natural satellites revolve around the earth due to the gravitational force between the earth and the satellite. The gravitational force between the earth and the satellite provides a necessary centripetal force to the satellite to move in a circular path around the earth.
  5. The atmosphere (envelope of gases) of the earth is possible due to gravitational force of the earth.
  6. Rainfall and snowfall is possible only due to gravitational force of the earth.
  7. We stay on the earth due to the gravitational force between the earth and us.

Question 8.
What is the acceleration of free fall ?
Answer:
Acceleration of free fall = 9.8 m s-2 ≈ 10 m s-2.

Question 9.
What do we call the gravitational force between the earth and an object ?
Answer:
Force of gravity.

Question 10..
Amit buys few grams of gold at the poles as per the instruction of one of his friends. He hands over the same when he meets him at the equator. Will the friend agree with the weight of gold bought ? If not, why ? (Hint: The value of g is greater at the poles than at the equator) (CBSE 2012, 2013)
Answer:
Weight = mg
Since value of g is greater at the poles than at the equator, so the weight of gold at the poles will be greater than the weight of gold at the equator. Hence, his friend will say that the weight of the gold is less than as told by Amit.

Question 11.
Why will a sheet of paper fall slower than one that is crumpled into a ball ?
Answer:
Since the area of a sheet of paper is more than the area of the paper crumpled into a small, therefore, a sheet of paper will experience a large opposing force due to air than the ball, while falling down. Hence, a sheet of paper falls slower than one that is crumpled into a ball.

Question 12.
Gravitational force on the surface of the moon is only 1/6 as strong as gravitational force on the earth.

Or

What is the weight in newtons of a 10 kg object on the moon and on the earth ?
Answer:
NCERT Solutions for Class 9 Science Chapter 10 Gravitation image - 7

Question 13.
A ball is thrown vertically upwards with a velocity of 49 m/s. Calculate
(i) the maximum height to which it rises,
(ii) the total time it takes to return to the surface of the earth.
(CBSE 2011, 2013, 2014)
Answer:
NCERT Solutions for Class 9 Science Chapter 10 Gravitation image - 8
The ball takes the same time to reach the ground from maximum height as time of ascent is equal to time of desent.
Total time taken = 5 s + 5 s = 10 s.

Question 14.
A stone is released from the top of a tower of height 19.6 m. Calculate its final velocity just before touching the ground. (CBSE 2011, 2013)
Answer:
NCERT Solutions for Class 9 Science Chapter 10 Gravitation image - 9

Question 15.
A stone is thrown vertically upward with an initial velocity of 40 m/s and is caught back. Taking g = 10 m/s2, find the maximum height reached by the stone. What is the net displacement and the total distance covered by the stone ?
(CBSE Sample Paper 2010; CBSE 2011, 2012, 2013)
Answer:
Here, u = 40 m/s,
g = -10 m/s2 (sign convention) v = 0 (at the maximum height)
NCERT Solutions for Class 9 Science Chapter 10 Gravitation image - 10
(ii) The stone after reaching the maximum height falls down and reach the ground.
Displacement of the stone = 0
and distance covered by the stone = 80 m + 80 m = 160 m.

Question 16.
Calculate the force of gravitation between the earth and the sun, given that the mass of the earth = 6 x 1024 kg and of the sun = 2 x 1030 kg.
Answer:
NCERT Solutions for Class 9 Science Chapter 10 Gravitation image - 11

Question 17.
A stone is allowed to fall from the top of a tower 100 m high and at the same time another stone is projected vertically upwards from the ground with a velocity of 25 m/s. Calculate when and where the two stones will meet ?
Answer:
Let t = time after which both stones meet .
S = distance of the stone dropped from the top of tower
(100 – S) = distance travelled by the projected stone.

NCERT Solutions for Class 9 Science Chapter 10 Gravitation image - 12
(iii) Put value of t = 4 s in equation (i),
S = 5 x 16 = 80 m
Thus, both the stones will meet at a distance of 80 m from the top of tower.

Question 18.
A ball thrown up vertically returns to the thrower after 6 s. Find
(a) the velocity with which it was thrown up,
(b) the maximum height it reaches, and
(c) its position after 4 s. (CBSE 2011)
Answer:
NCERT Solutions for Class 9 Science Chapter 10 Gravitation image - 13

NCERT Solutions for Class 9 Science Chapter 10 Gravitation

Hope given NCERT Solutions for Class 9 Science Chapter 10 are helpful to complete your science homework.

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RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2

RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2

These Solutions are part of RD Sharma Class 9 Solutions. Here we have given RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2

Other Exercises

Question 1.
Find the area of a quadrilateral ABCD in which AB = 3cm, BC = 4cm, CD = 4cm, DA = 5cm and AC = 5cm (NCERT)
Solution:
In the quadrilateral, AC is the diagonal which divides the figure into two triangles
Now in ∆ABC, AB = 3 cm, BC = 4cm, AC = 5cm
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q1.1
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q1.2

Question 2.
The sides of a quadrangular field taken in order are 26 m, 27 m, 7 m and 24 m respectively. The angle contained by the last two sides is a right angle. Find its area.
Solution:
In quad. ABCD, AB = 26 m, BC = 27 m CD = 7m, DA = 24 m, ∠CDA = 90°
Join AC,
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q2.1
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q2.2

Question 3.
The sides of a quadrilateral taken in order are 5, 12, 14 and 15 metres respectively, and the angle contained by the first two sides is a right angle. Find its area.
Solution:
In quad. ABCD,
AB = 5m, BC = 12 m, CD = 14m,
DA = 15 m and ∠ABC = 90°
Join AC,
Now in right ∆ABC,
AC² = AB² + BC² = (5)² + (12)²
= 25 + 144 = 169 = (13)²
∴ AC = 13 m
Now area of right ∆ABC
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q3.1
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q3.2

Question 4.
A park, in shape of a quadrilateral ABCD, has ∠C = 90°, AB = 9m, BC = 12m, CD = 5m and AD = 8m. How much area does it occupy? (NCERT)
Solution:
In quadrilateral ABCD,
AB = 9m, BC = 12m, CD = 5m and
DA = 8m, ∠C = 90°
Join BD,
Now in right ∆BCD,
BD² = BC²+ CD² = (12)² + (5)²
= 144 + 25 = 169 = (13)²
∴ BD = 13m
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q4.1
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q4.2

Question 5.
Find the area of a rhombus whose perimeter is 80m and one of whose diagonal is 24m.
Solution:
Perimeter of rhombus ABCD = 80 m
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q5.1
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q5.2

Question 6.
A rhombus sheet whose perimeter = 32 m and whose one diagonal is 10 m long, is painted on both sides at the rate of ₹5 per m². Find the cost of painting.
Solution:
Perimeter of the rhombus shaped sheet = 32 m
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q6.1
∴ Length of each side = \(\frac { 32 }{ 4 }\) = 8m
and length of one diagonal AC = 10 m
In ∆ABC, sides are 8m, 8m, 10m
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q6.2

Question 7.
Find the area of a quadrilateral ABCD in which AD = 24 cm, ∠BAD = 90° and BCD forms an equilateral triangle whose each side is equal to 26 cm. (Take \(\sqrt { 3 } \) = 1.73 )
Solution:
In quadrilateral ABCD, AD = 24cm, ∠BAD = 90°
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q7.1
BCD is an equilateral triangle with side 26cm
In right ∆ABD,
BD² = AB²+ AD²
(26)² = AB² + (24)²
⇒ 676 = AB² + 576
AB² = 676 – 576 = 100 = (10)²
∴ AB = 10cm
Now area of right ∆ABD,
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q7.2

Question 8.
Find the area of a quadrilateral ABCD in which AB = 42cm, BC = 21cm, CD = 29 cm, DA = 34 cm and diagonal BD = 20 cm.
Solution:
In quadrilateral ABCD,
AB = 42 cm, BC = 21 cm, CD = 29cm DA = 34 cm, BD = 20 cm
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q8.1
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q8.2

Question 9.
The adjacent sides of a parallelogram ABCD measures 34 cm and 20 cm, and the diagonal AC measures 42 cm. Find the area of the parallelogram.
Solution:
In ||gm ABCD,
AB = 34cm, BC = 20 cm
and AC = 42 cm
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q9.1
∵ The diagonal of a parallelogram divides into two triangles equal in area,
Now area of ∆ABC,
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q9.2

Question 10.
Find the area of the blades of the magnetic compass shown in figure. (Take \(\sqrt { 11 } \) = 3.32).
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q10.1
Solution:
ABCD is a rhombus with each side 5cm and one diagonal 1cm
Diagonal BD divides into two equal triangles Now area of ∆ABD,
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q10.2

Question 11.
A triangle and a parallelogram have the same base and the same area. If the sides of the triangle are 13 cm, 14 cm and 15 cm and the parallelogram stands on the base 14 cm, find the height of the parallelogram.
Solution:
Area of a triangle with same base and area of a 11gm with equal sides of triangle are 13, 14, 15 cm
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q11.1
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q11.2

Question 12.
Two parallel sides of a trapezium are 60cm and 77 cm and other sides are 25 cm and 26 cm. Find the area of the trapezium.
Solution:
In trapezium ABCD, AB || DC
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q12.1
AB = 77cm, BC = 26 cm, CD 60cm DA = 25 cm
Through, C, draw CE || DA meeting AB at E
∴ AE = CD = 60 cm and EB = 77 – 60 = 17 cm,
CE = DA = 25 cm
Now area of ∆BCE, with sides 17 cm, 26 cm, 25 cm
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q12.2
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q12.3

Question 13.
Find the perimeter and area of the quadrilateral ABCD in which AB = 17 cm, AD = 9cm, CD = 12cm, ∠ACB = 90° and AC = 15cm.
Solution:
In right ΔABC, ∠ACB = 90°
AB² = AC² + BC²
(17)² = (15)²+ BC² = 289 = 225 + BC²
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q13.1
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q13.2

Question 14.
A hand fan is made by stitching 10 equal size triangular strips of two different types of paper as shown figure. The dimensions of equal strips are 25 cm, 25 cm and 14 cm. Find the area of each types of paper needed to make the hand fan.
Solution:
In the figure, a hand fan has 5 isosceles and triangle. With sides 25 cm, 25 cm and 14 cm each.
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.2 Q14.1

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RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.1

RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.1

These Solutions are part of RD Sharma Class 9 Solutions. Here we have given RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.1

Other Exercises

Question 1.
Find the area of a triangle whose sides are respectively 150 cm, 120 cm and 200 cm.
Solution:
Sides of triangle are 120 cm, 150 cm, 200 cm
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.1 Q1.1
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.1 Q1.2

Question 2.
Find the area of a triangle whose sides are 9 cm, 12 cm and 15 cm.
Solution:
Sides of a triangle are 9 cpi, 12 cm, 15 cm
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.1 Q2.1

Question 3.
Find the area of a triangle two sides of which are 18 cm and 10 cm and the perimeter is 42 cm.
Solution:
Perimeter of a triangle = 42 cm
Two sides are 18 cm and 10 cm
Third side = 42 – (18 + 10)
= 42 – 28 = 14 cm
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.1 Q3.1

Question 4.
In a ∆ABC, AB = 15 cm, BC = 13 cm and AC = 14 cm. Find the area of ∆ABC and hence its altitude on AC.
Solution:
Sides of triangle ABC are AB = 15 cm, BC = 13 cm, AC = 14 cm
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.1 Q4.1
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.1 Q4.2

Question 5.
The perimeter of a triangular field is 540 m and its sides are in the ratio 25 : 17 : 12. Find the area of the triangle. [NCERT]
Solution:
Perimeter of a triangle = 540 m
Ratio in sides = 25 : 17 : 12
Sum of ratios = 25 + 17 + 12 = 54
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.1 Q5.1
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.1 Q5.2

Question 6.
The perimeter of a triangle is 300 m. If its sides are in the ratio 3:5:7. Find the area of the triangle. [NCERT]
Solution:
Perimeter of a triangle = 300 m
Ratio in the sides = 3 : 5 : 7
∴ Sum of ratios = 3 + 5 + 7= 15
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.1 Q6.1

Question 7.
The perimeter of a triangular field is 240 dm. If two of its sides are 78 dm and 50 dm, find the length of the perpendicular on the side of length 50 dm from the opposite vertex.
Solution:
Perimeter of a triangular field = 240 dm
Two sides are 78 dm and 50 dm
∴ Third side = 240 – (78 + 50)
= 240 – 128 = 112 dm
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.1 Q7.1

Question 8.
A triangle has sides 35 cm, 54 cm and 61 cm long. Find its area. Also, find the smallest of its altitudes.
Solution:
Sides of a triangle are 35 cm, 54 cm, 61 cm
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.1 Q8.1

Question 9.
The lengths of the sides of a triangle are in the ratio 3:4:5 and its perimeter is 144 cm. Find the area of the triangle and the height corresponding to the longest side.
Solution:
Ratio in the sides of a triangle = 3:4:5
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.1 Q9.1
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.1 Q9.2

Question 10.
The perimeter of an isosceles triangle is 42 cm and its base is (3/2) times each of the equal sides. Find the length of each side of the triangle, area of the triangle and the height of the triangle.
Solution:
Perimeter of an isosceles triangle = 42 cm
Base = \(\frac { 3 }{ 2 }\) of its one of equal sides
Let each equal side = x, then 3
Base = \(\frac { 3 }{ 2 }\) x
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.1 Q10.1
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.1 Q10.2

Question 11.
Find the area of the shaded region in figure.
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.1 Q11.1
Solution:
In ∆ABC, AC = 52 cm, BC = 48 cm
and in right ∆ADC, ∠D = 90°
AD = 12 cm, BD = 16 cm
∴ AB²=AD² + BD² (Pythagoras Theorem)
(12)² + (16)² = 144 + 256 = 400 = (20)²
∴ AB = 20 cm
RD Sharma Class 9 Solutions Chapter 17 Constructions Ex 17.1 Q11.2

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RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.3

RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.3

These Solutions are part of RD Sharma Class 9 Solutions. Here we have given RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.3

Other Exercises

Question 1.
Construct a ∆ABC in which BC = 3.6 cm, AB + AC = 4.8 cm and ∠B = 60°.
Solution:
Steps of construction :
(i) Draw a line segment BC = 3.6 cm.
(ii) At B, draw a ray BX making an angle of 60° and cut off BE = 4.8 cm.
(iii) Join EC.
(iv) Draw perpendicular bisector of CE which intersects BE at A.
(v) Join AC.
∆ABC is the required triangle.
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.3 Q1.1

Question 2.
Construct a ∆ABC in which AB + AC = 5.6 cm, BC = 4.5 cm and ∠B = 45°.
Solution:
Steps of construction :
(i) Draw a line segment BC = 4.5 cm.
(ii) At B, draw a ray BX making an angle of 45° and cut off BE = 5.6 cm and join CE.
(iii) Draw the perpendicular bisector of CE which intersects BE at A.
(iv) Join AC.
∆ABC is the required triangle.
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.3 Q2.1

Question 3.
Construct a AABC in which BC = 3.4 cm, AB – AC = 1.5 cm and ∠B = 45°.
Solution:
Steps of construction :
(i) Draw a line segment BC = 3.4 cm.
(ii) At B, draw a ray BX making an angle of 45° and cut off BE = 1.5 cm.
(iii) Join EC.
(iv) Draw the perpendicular bisector of CE which intersects BE produced at A.
(v) Join AC.
∆ABC is the required triangle.
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.3 Q3.1

Question 4.
Using ruler and compasses only, construct a ∆ABC, given base BC = 7 cm, ∠ABC = 60° and AB + AC = 12 cm.
Solution:
Steps of construction :
(i) Draw a line segment BC = 7 cm!
(ii) At B, draw a ray BX making an angle of 60° and cut off BE = 12 cm.
(iii) Join EC.
(iv) Draw the perpendicular bisector of EC which intersects BE at A.
(v) Join AC.
∆ABC is the required triangle.
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.3 Q4.1

Question 5.
Construct a right-angled triangle whose perimeter is equal to 10 cm and one acute angle equal to 60°.
Solution:
Steps of construction :
(i) Draw a line segment PQ = 10 cm.
(ii) At P, draw a ray PX making an angle of 90° and at Q, QY making an angle of 60°.
(iii) Draw the angle bisectors of ∠P and ∠Q meeting each other at A.
(iv) Draw the perpendicular bisectors of AP and AQ intersecting PQ at B and C respectively,
(v) Join AB and AC.
∆ABC is the required triangle.
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.3 Q5.1

Question 6.
Construct a triangle ABC such that BC = 6cm, AB = 6 cm and median AD = 4 cm.
Solution:
Steps of construction :
(i) Draw a line segment BC = 6 cm and bisect it at D.
(ii) With centre B and radius 6 cm and with centre D and radius 4 cm, draw arcs intersecting each other at A.
(iii) Join AD and AB and AC.
Then ∆ABC is the required triangle.
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.3 Q6.1

Question 7.
Construct a right triangle ABC whose base BC is 6 cm and the sum of hypotenuse AC and other side AB is 10 cm.
Solution:
Steps of construction :
(i) Draw a line segment BC = 6 cm
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.3 Q7.1
(ii) At B, draw a ray BX making an angle of 90° and cut off BE = 10 cm.
(iii) Join EC and draw the perpendicular bisector of CE which intersects BE at A.
(iv) Join AC.
∆ABC is the required triangle.

Question 8.
Construct a triangle whose perimeter is 6.4 cm, and angles at the base are 60° and 45°.
Solution:
Steps of construction :
(i) Draw a line segment PQ = 6.4 cm.
(ii) At P draw a ray PX making an angle of 60° and at Q, a ray QY making an angle of 45°.
(iii) Draw the bisector of ∠P and ∠Q meeting each other at A.
(iv) Draw the perpendicular bisectors of PA and QA intersecting PQ at B and C respectively.
(v) Join AB and AC.
∆ABC is the required triangle.
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.3 Q8.1

Question 9.
Using ruler and compasses only, construct a ∆ABC, from the following data:
AB + BC + CA = 12 cm, ∠B = 45° and ∠C = 60°.
Solution:
Steps of construction :
(i) Draw a line segment PQ = 12 cm.
(ii) Draw ray PX at P making are angle of 45° and at Q, QY making an angle of 60°.
(Hi) Draw the angle bisectors of ∠P and ∠Q meeting each other at A.
(v) Draw the perpendicular bisector of AP and AQ intersecting PQ at B and C respectively.
(v) Join AB and AC.
∆ABC is the required triangle.
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.3 Q9.1

Question 10.
Construct a triangle XYZ in which ∠Y = 30° , ∠Z = 90° XY +YZ + ZX = 11
Solution:
Steps of construction :
(i) Draw a line segment PQ =11 cm.
(ii) At P, draw a ray PL making an angle of 30° and Q, draw another ray QM making an angle of 90°.
(iii) Draw the angle bisector of ∠P and ∠Q intersecting each other at X.
(iv) Draw the perpendicular bisector of XP and XQ. Which intersect PQ at Y and Z respectively.
(v) Join XY and XZ.
Then ∆XYZ is the required triangle
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.3 Q10.1

Hope given RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.3 are helpful to complete your math homework.

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RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.2

RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.2

These Solutions are part of RD Sharma Class 9 Solutions. Here we have given RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.2

Other Exercises

Question 1.
Draw an angle and label it as ∠BAC. Construct another angle, equal to ∠BAC.
Solution:
Steps of construction :
(i) Draw an angle BAC.
(ii) Draw a line DF.
(iii) With centre A and D, draw arcs of equal radius which intersect AC at L and AB at M and DF at P.
(iv) Cut off PQ = LM and join DQ and produce it to E, then
∠EDF = ∠BAC.
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.2 Q1.1

Question 2.
Draw an obtuse angle. Bisect it. Measure each of the angles so obtained.
Solution:
Steps of construction :
(i) Draw an angle ABC which is an obtuse i.e. more than 90°.
(ii) With centre B and a suitable radius draw an arc meeting BC at E and AB at F.
(iii) With centre E and F, and radius more than half of EF draw arcs intersecting each other at G.
(iv) Join BG and produce it to D.
ThenBD is die bisector of ∠ABC.
On measuring each part, we find each angle = 53°.
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.2 Q2.1

Question 3.
Using your protractor, draw an angle of measure 108°. With this angle as given, draw an angle of 54°.
Solution:
Steps of construction :
(i) With the help of protractor draw an angle ABC = 108°.
As 54° = \(\frac { 1 }{ 2 }\) x 108°
∴ We shall bisect it.
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.2 Q3.1
(ii) With centre B and a suitable radius, draw an arc meeting BC at E and AB at F.
(iii) With centre E and F, and radius more than half of EF, draw arcs intersecting each other at G
(iv) Join BG and produce it to D.
Then ∠DBC = 54°.

Question 4.
Using protractor, draw a right angle. Bisect it to get an angle of measure 45°.
Solution:
Steps of construction :
(i) Using protractor, draw a right angle ∆ABC.
i. e. ∠ABC = 90°.
(ii) With centre B and a suitable radius, draw an arc which meets BC at E and BA at F.
(iii) With centre E and F, draw arcs intersecting each other at G.
(iv) Join BG and produce it to D.
Then BD is the bisector of ∠ABC.
∴ ∠DBC =\(\frac { 1 }{ 2 }\) x 90° = 45°.
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.2 Q4.1

Question 5.
Draw a linear pair of angles. Bisect each of the two angles. Verify that the two bisecting rays are perpendicular to each other.
Solution:
Steps of construction :
(i) Draw a linear pair ∠DCA and ∠DCB.
(ii) Draw the bisectors of ∠DCA and ∠DCB. Forming ∠ECF on measuring we get ∠ECF = 90°.
Verification : ∵∠DCA + ∠DCB = 180°
⇒ \(\frac { 1 }{ 2 }\) ∠DCA + \(\frac { 1 }{ 2 }\) ∠DCB = 180° x \(\frac { 1 }{ 2 }\) = 90°
∴ ∠ECF = 90°
i.e. EC and FC are perpendicular to each other.
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.2 Q5.1

Question 6.
Draw a pair of vertically opposite angles. Bisect each of the two angles. Verify that the bisecting rays are in the same line
Solution:
Steps of construction :
(i) Draw two lines AB and CD intersecting each other at O.
(ii) Draw the bisector of ∠AOD and also the bisector of ∠BOC. Which are OP and OQ respectively. We see that OP and OQ are in the same straight line.
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.2 Q6.1

Question 7.
Using ruler and compasses only, draw a right angle.
Solution:
Steps of construction :
(i) Draw a line segment BC.
(ii) With centre B and a suitable radius, draw an arc meeting BC at E.
(iii) With centre E and same radius, cut off arcs EF and FG.
(iv) Bisect arc FG at H.
(v) Join BH and produce it to A.
Then ∠ABC = 90°.
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.2 Q7.1

Question 8.
Using ruler and compasses only, draw an angle of measure 135°.
Solution:
Steps of construction :
(i) Draw a line DC and take a point B on it.
(ii) With centre B and a suitable radius draw an arc meeting BC at P.
(iii) With centre P, cut off arcs PQ, QR and RS.
(iv) Bisect as QR at T and join BT and produce it to E.
(v) Now bisect the arc KS at RL.
(vi) Join BL and produce it to A.
Now ∠ABC = 135°.
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.2 Q8.1

Question 9.
Using a protractor, draw an angle of measure 72°. With this angle as given, draw angles of measure 36° and 54°.
Solution:
Steps of construction :
(i) Draw an angle ABC = 12° with the help of protractor.
(ii) With centre B and a suitable radius, draw an arc EF.
(iii) With centre E and F, draw arcs intersecting
each other at G and produce it to D.
Then BD is the bisector of ∠ABC.
∴ ∠DBC = 72° x \(\frac { 1 }{ 2 }\) = 36°.
(iv) Again bisect ∠ABD in the same way then PB is the bisector of ∠ABD.
∴ ∠PBC = 36° + \(\frac { 1 }{ 2 }\) x 36°
= 36° + 18° = 54°
Hence ∠PBC = 54°
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.2 Q9.1

Question 10.
Construct the following angles at the initial point of a given ray and justify the construction:
(i) 45°
(ii) 90°
Solution:
(i) 45°
Steps of construction :
(a) Draw a line segment BC.
(b) With centre B and a suitable radius draw an arc meeting BC at E.
(c) With centre E, cut off equal arcs EF and FG.
(d) Bisect FG at H.
(e) Join BH and produce to X so that ∠XBC = 90°.
(f) Bisect ∠XBC so that ∠ABC = 45°.
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.2 Q10.1
(ii) 90°
Steps of construction :
(a) Draw a line segment BC.
(b) With centre B and a suitable radius, draw an arc meeting BC at E and with centre E cut off arcs from E, EF = FG
(c) Now bisect the arc EG at H.
(d) Join BH and produce it to A.
∴ ∠ABC = 90°.
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.2 Q10.2

Question 11.
Construct the angles of the following measurements:
(i) 30°
(ii) 75°
(iii) 105°
(iv) 135°
(v) 15°
(vi) 22 \(\frac { 1 }{ 2 }\)°
Solution:
(i) 30°
Steps of construction :
(a) Draw a line segment BC.
(b) With centre B and a suitable radius draw an arc meeting BC at E.
(c) Cut off arcs EF and bisect it at G.
So that ∠ABC = 30°.
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.2 Q11.1
(ii) 75°
Steps of construction :
(a) Draw a line segment BC.
(b) With centre B and a suitable radius, draw an arc meeting BC at E.
(c) Cut off arc EF = FG from E.
(d) Bisect the arc FG at K and join BK so that ∠KBC = 90°.
(e) Now bisect arc HF at L and join BL and produce it to A so that ∠ABC = 75°.
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.2 Q11.2
(iii) 105°
Steps of construction :
(a) Draw a line segment BC.
(b) With centre B and a suitable radius draw an arc meeting BC at E.
(c) From E, cut off arc EF = FG and divide FG at H.
(d) Join BH meeting the arc at K.
(e) Now bisect the arc KG at L.
Join BL and produce it to A.
Then ∠ABC = 105°.
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.2 Q11.3
(iv) 135°
Steps of construction :
(a) Draw a line segment BC.
(b) With centre B and a suitable radius, draw an arc meeting BC at E.
(c) From E, cut off EF = FG = GH.
(d) Bisect arc FG at K, and join them.
(e) Bisect arc KH at L.
(f) Join BL and produce it to A, then ∠ABC = 135°.
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.2 Q11.4
(v) 15°
Steps of construction :
(a) Draw a line segment BC.
(b) With centre B and a suitable radius, draw an arc meeting BC at E.
(c) Cut off arc EF from E and bisect it at G. Then ∠GBC = 30°.
(d) Again bisect the arc EJ at H.
(e) Join BH and produce it to A.
Then ∠ABC = 15°.
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.2 Q11.5
(vi) 22 \(\frac { 1 }{ 2 }\)°
Steps of construction :
(a) Draw a line segment BC.
(b) With centre B and a suitable radius, draw an arc and from E, cut off EF = FG
(c) Bisect FG at H so that ∠HBC = 90°.
(d) Now bisect ∠HBC at K. So that ∠YBC = 45°.
(e) Again bisect ∠YBC at J. So thttt ∠ABC = 22 \(\frac { 1 }{ 2 }\)°
RD Sharma Class 9 Solutions Chapter 16 Circles Ex 16.2 Q11.6

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