Page 1
RD Sharma Solutions for Class 8 Maths Chapter 18
– Practical Geometry (Constructions)
EXERCISE 18.3 PAGE NO: 18.8
1. Construct a quadrilateral ABCD in which AB = 3.8 cm, BC = 3.4 cm, CD = 4.5
cm, AD = 5 cm and ?B = 80°.
Solution:
The given details are AB = 3.8 cm, BC = 3.4 cm, CD = 4.5 cm, AD = 5 cm and ?B =
80°.
Steps to construct a quadrilateral:
Step 1- Draw a line AB = 3.8cm
Step 2- Construct and angle of 80
o
at B.
Step 3- Cut an arc of radius 3.4cm with B as the center to mark that point as C.
Step 4- Cut an arc of radius 5cm with A as the center to mark that point as D.
Step 5- Cut an arc of radius 4.5cm with C as the center to intersect at point D.
Step 6- Now join BC, AD and CD
2. Construct a quadrilateral ABCD given that AB = 8 cm, BC = 8 cm, CD = 10
cm, AD = 10 cm and ?A = 45°.
Solution:
The given details are AB = 8 cm, BC = 8 cm, CD = 10 cm, AD = 10 cm and ?A = 45°.
Steps to construct a quadrilateral:
Step 1- Draw a line AB = 8cm
Step 2- Construct and angle of 45
o
at A.
Step 3- Cut an arc of radius 10cm with A as the center to mark that point as D.
Step 4- Cut an arc of radius 10cm with D as the center to mark that point as C.
Step 5- Cut an arc of radius 8cm with B as the center to intersect at point C.
Step 6- Now join AD, DC and BC
Page 2
RD Sharma Solutions for Class 8 Maths Chapter 18
– Practical Geometry (Constructions)
EXERCISE 18.3 PAGE NO: 18.8
1. Construct a quadrilateral ABCD in which AB = 3.8 cm, BC = 3.4 cm, CD = 4.5
cm, AD = 5 cm and ?B = 80°.
Solution:
The given details are AB = 3.8 cm, BC = 3.4 cm, CD = 4.5 cm, AD = 5 cm and ?B =
80°.
Steps to construct a quadrilateral:
Step 1- Draw a line AB = 3.8cm
Step 2- Construct and angle of 80
o
at B.
Step 3- Cut an arc of radius 3.4cm with B as the center to mark that point as C.
Step 4- Cut an arc of radius 5cm with A as the center to mark that point as D.
Step 5- Cut an arc of radius 4.5cm with C as the center to intersect at point D.
Step 6- Now join BC, AD and CD
2. Construct a quadrilateral ABCD given that AB = 8 cm, BC = 8 cm, CD = 10
cm, AD = 10 cm and ?A = 45°.
Solution:
The given details are AB = 8 cm, BC = 8 cm, CD = 10 cm, AD = 10 cm and ?A = 45°.
Steps to construct a quadrilateral:
Step 1- Draw a line AB = 8cm
Step 2- Construct and angle of 45
o
at A.
Step 3- Cut an arc of radius 10cm with A as the center to mark that point as D.
Step 4- Cut an arc of radius 10cm with D as the center to mark that point as C.
Step 5- Cut an arc of radius 8cm with B as the center to intersect at point C.
Step 6- Now join AD, DC and BC
RD Sharma Solutions for Class 8 Maths Chapter 18
– Practical Geometry (Constructions)
3. Construct a quadrilateral ABCD in which AB = 7.7 cm, BC = 6.8 cm, CD = 5.1
cm, AS = 3.6 cm and ?C = 120°.
Solution:
The given details are AB = 7.7 cm, BC = 6.8 cm, CD = 5.1 cm, AS = 3.6 cm and ?C =
120°.
Steps to construct a quadrilateral:
Step 1- Draw a line DC = 5.1cm
Step 2- Construct and angle of 120
o
at C.
Step 3- Cut an arc of radius 6.8cm with C as the center to mark that point as B.
Step 4- Cut an arc of radius 7.7cm with B as the center to mark that point as A.
Step 5- Cut an arc of radius 3.6cm with D as the center to intersect at point A.
Step 6- Now join CB, BA and DA
Page 3
RD Sharma Solutions for Class 8 Maths Chapter 18
– Practical Geometry (Constructions)
EXERCISE 18.3 PAGE NO: 18.8
1. Construct a quadrilateral ABCD in which AB = 3.8 cm, BC = 3.4 cm, CD = 4.5
cm, AD = 5 cm and ?B = 80°.
Solution:
The given details are AB = 3.8 cm, BC = 3.4 cm, CD = 4.5 cm, AD = 5 cm and ?B =
80°.
Steps to construct a quadrilateral:
Step 1- Draw a line AB = 3.8cm
Step 2- Construct and angle of 80
o
at B.
Step 3- Cut an arc of radius 3.4cm with B as the center to mark that point as C.
Step 4- Cut an arc of radius 5cm with A as the center to mark that point as D.
Step 5- Cut an arc of radius 4.5cm with C as the center to intersect at point D.
Step 6- Now join BC, AD and CD
2. Construct a quadrilateral ABCD given that AB = 8 cm, BC = 8 cm, CD = 10
cm, AD = 10 cm and ?A = 45°.
Solution:
The given details are AB = 8 cm, BC = 8 cm, CD = 10 cm, AD = 10 cm and ?A = 45°.
Steps to construct a quadrilateral:
Step 1- Draw a line AB = 8cm
Step 2- Construct and angle of 45
o
at A.
Step 3- Cut an arc of radius 10cm with A as the center to mark that point as D.
Step 4- Cut an arc of radius 10cm with D as the center to mark that point as C.
Step 5- Cut an arc of radius 8cm with B as the center to intersect at point C.
Step 6- Now join AD, DC and BC
RD Sharma Solutions for Class 8 Maths Chapter 18
– Practical Geometry (Constructions)
3. Construct a quadrilateral ABCD in which AB = 7.7 cm, BC = 6.8 cm, CD = 5.1
cm, AS = 3.6 cm and ?C = 120°.
Solution:
The given details are AB = 7.7 cm, BC = 6.8 cm, CD = 5.1 cm, AS = 3.6 cm and ?C =
120°.
Steps to construct a quadrilateral:
Step 1- Draw a line DC = 5.1cm
Step 2- Construct and angle of 120
o
at C.
Step 3- Cut an arc of radius 6.8cm with C as the center to mark that point as B.
Step 4- Cut an arc of radius 7.7cm with B as the center to mark that point as A.
Step 5- Cut an arc of radius 3.6cm with D as the center to intersect at point A.
Step 6- Now join CB, BA and DA
RD Sharma Solutions for Class 8 Maths Chapter 18
– Practical Geometry (Constructions)
4. Construct a quadrilateral ABCD in which AB = BC = 3 cm, AD = CD = 5 cm
and ?B = 120°.
Solution:
The given details are AB = BC = 3 cm, AD = CD = 5 cm and ?B = 120°.
Steps to construct a quadrilateral:
Step 1- Draw a line AB = 3cm
Step 2- Construct and angle of 120
o
at B.
Step 3- Cut an arc of radius 3cm with B as the center to mark that point as C.
Step 4- Cut an arc of radius 5cm with C as the center to mark that point as D.
Step 5- Cut an arc of radius 5cm with A as the center to intersect at point D.
Step 6- Now join BC, CD and DA
5. Construct a quadrilateral ABCD in which AB = 2.8 cm, BC = 3.1 cm, CD = 2.6 cm
and DA = 3.3 cm and ?A = 60°.
Solution:
The given details are AB = 2.8 cm, BC = 3.1 cm, CD = 2.6 cm and DA = 3.3 cm
and ?A = 60°.
Steps to construct a quadrilateral:
Step 1- Draw a line AB = 2.8cm
Step 2- Construct and angle of 60
o
at A.
Step 3- Cut an arc of radius 3.3cm with A as the center to mark that point as D.
Step 4- Cut an arc of radius 2.6cm with D as the center to mark that point as C.
Step 5- Cut an arc of radius 3.1cm with B as the center to intersect at point C.
Step 6- Now join AD, DC and CB
Page 4
RD Sharma Solutions for Class 8 Maths Chapter 18
– Practical Geometry (Constructions)
EXERCISE 18.3 PAGE NO: 18.8
1. Construct a quadrilateral ABCD in which AB = 3.8 cm, BC = 3.4 cm, CD = 4.5
cm, AD = 5 cm and ?B = 80°.
Solution:
The given details are AB = 3.8 cm, BC = 3.4 cm, CD = 4.5 cm, AD = 5 cm and ?B =
80°.
Steps to construct a quadrilateral:
Step 1- Draw a line AB = 3.8cm
Step 2- Construct and angle of 80
o
at B.
Step 3- Cut an arc of radius 3.4cm with B as the center to mark that point as C.
Step 4- Cut an arc of radius 5cm with A as the center to mark that point as D.
Step 5- Cut an arc of radius 4.5cm with C as the center to intersect at point D.
Step 6- Now join BC, AD and CD
2. Construct a quadrilateral ABCD given that AB = 8 cm, BC = 8 cm, CD = 10
cm, AD = 10 cm and ?A = 45°.
Solution:
The given details are AB = 8 cm, BC = 8 cm, CD = 10 cm, AD = 10 cm and ?A = 45°.
Steps to construct a quadrilateral:
Step 1- Draw a line AB = 8cm
Step 2- Construct and angle of 45
o
at A.
Step 3- Cut an arc of radius 10cm with A as the center to mark that point as D.
Step 4- Cut an arc of radius 10cm with D as the center to mark that point as C.
Step 5- Cut an arc of radius 8cm with B as the center to intersect at point C.
Step 6- Now join AD, DC and BC
RD Sharma Solutions for Class 8 Maths Chapter 18
– Practical Geometry (Constructions)
3. Construct a quadrilateral ABCD in which AB = 7.7 cm, BC = 6.8 cm, CD = 5.1
cm, AS = 3.6 cm and ?C = 120°.
Solution:
The given details are AB = 7.7 cm, BC = 6.8 cm, CD = 5.1 cm, AS = 3.6 cm and ?C =
120°.
Steps to construct a quadrilateral:
Step 1- Draw a line DC = 5.1cm
Step 2- Construct and angle of 120
o
at C.
Step 3- Cut an arc of radius 6.8cm with C as the center to mark that point as B.
Step 4- Cut an arc of radius 7.7cm with B as the center to mark that point as A.
Step 5- Cut an arc of radius 3.6cm with D as the center to intersect at point A.
Step 6- Now join CB, BA and DA
RD Sharma Solutions for Class 8 Maths Chapter 18
– Practical Geometry (Constructions)
4. Construct a quadrilateral ABCD in which AB = BC = 3 cm, AD = CD = 5 cm
and ?B = 120°.
Solution:
The given details are AB = BC = 3 cm, AD = CD = 5 cm and ?B = 120°.
Steps to construct a quadrilateral:
Step 1- Draw a line AB = 3cm
Step 2- Construct and angle of 120
o
at B.
Step 3- Cut an arc of radius 3cm with B as the center to mark that point as C.
Step 4- Cut an arc of radius 5cm with C as the center to mark that point as D.
Step 5- Cut an arc of radius 5cm with A as the center to intersect at point D.
Step 6- Now join BC, CD and DA
5. Construct a quadrilateral ABCD in which AB = 2.8 cm, BC = 3.1 cm, CD = 2.6 cm
and DA = 3.3 cm and ?A = 60°.
Solution:
The given details are AB = 2.8 cm, BC = 3.1 cm, CD = 2.6 cm and DA = 3.3 cm
and ?A = 60°.
Steps to construct a quadrilateral:
Step 1- Draw a line AB = 2.8cm
Step 2- Construct and angle of 60
o
at A.
Step 3- Cut an arc of radius 3.3cm with A as the center to mark that point as D.
Step 4- Cut an arc of radius 2.6cm with D as the center to mark that point as C.
Step 5- Cut an arc of radius 3.1cm with B as the center to intersect at point C.
Step 6- Now join AD, DC and CB
RD Sharma Solutions for Class 8 Maths Chapter 18
– Practical Geometry (Constructions)
6. Construct a quadrilateral ABCD in which AB = BC = 6 cm, AD = DC = 4.5 cm
and ?B = 120°.
Solution:
The given details are AB = BC = 6 cm, AD = DC = 4.5 cm and ?B = 120°.
Steps to construct a quadrilateral:
Step 1- Draw a line AB = 6cm
Step 2- Construct and angle of 120
o
at B.
Step 3- Cut an arc of radius 6cm with B as the center to mark that point as C.
Here, AC is about 10.3cm in length which is greater than AD + CD = 4.5+4.5=9cm
We know that sum of the two sides of a triangle is always greater than the third side.
AD + CD < AC
? Construction is not possible.
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