The DAV Class 7 Maths Solution and **DAV Class 7 Maths Chapter 10 Worksheet 3** Solutions of Construction of Triangles offer comprehensive answers to textbook questions.

## DAV Class 7 Maths Ch 10 WS 3 Solutions

Question 1.

Construct a ∆ABC in which BC = 4 cm, ∠B = 50° and ∠C = 70°

Answer:

Steps of Construction:

- Draw BC = 4 cm.
- Draw ∠B = 50° and ∠C = 70° to cut each other at A.
- ∆ABC is the required triangle.

Question 2.

Draw a ∆ABC in which BC = 8 cm, ∠B = 50° and ∠A = 50°.

Answer:

Steps of Construction:

- Draw BC = 8 cm.
- Draw ∠B = 50° and ∠C = 80° to meet at A.

Question 3.

Draw a triangle ABC with AB = 4.5 cm, ∠ABC = 35°, ∠ACB = 65°.

Answer:

Steps of Construction:

- Draw AB = 4.5 cm. c
- Draw ∠B = 35°
- Draw ∠A = 80°

[∵ ∠A = 180° — (35° + 65°) = 80°] - They meet at C.
- ∆ABC is the required triangle. A

Question 4.

Construct a ∆PQR with PQ = 7.5 cm, ∠RPQ = 45° ∠RQP = 45°. Measure the third angle. What kind of a triangle is it?

Answer:

Steps of Construction:

- Draw PQ = 7.5 cm.
- Draw an angle of 45° at P and at Q.
- The two angle lines meet at R.
- ∆PRQ is the required triangle.
- ∠PRQ = 90°
- ∆PQR is an isosceles right angled triangle.

Question 5.

Construct a ∆PQR with ∠P = 70°, ∠Q = 120° and side PQ = 5.2 cm. Is the construction possible?

Answer:

Steps of Construction:

- Draw PQ = 5.2 cm
- Draw ∠Q = 120° and ∠P = 70°
- The two angle lines do not meet any point.

[∵ 120° + 70° > 180° ⇒ 190° > 180°] - Therefore, the construction of ∆PQR is not possible.

Question 6.

Construct a ∆ABC in which BC

Answer:

Steps of Construction:

- Draw BC = 6 cm.
- Draw ∠B = 40° and ∠C = 110°.
- The two angle sides meet at A.
- ∆ABC is the required triangle.