Page 215 - Start Up Mathematics_7

5. The ____________ angle of a triangle is equal to the sum of the interior opposite angles.

6. In the adjoining figure, if ∠B > ∠E then AC _______ DF.
7. In a right triangle the square of the ____________ is equal to the ____________ of the squares
of the other two sides.

Answer in One Word or a Line
1. What are the various possibilities if two lines lie in a plane?

2. How do you construct a line parallel to a given line from a point outside it?
3. Before starting construction of a triangle what should be done?

4. What is SSS construction criterion?
5. Can a triangle be constructed if its two sides and the included angle are given?

6. Which two instruments are required to draw a scalene triangle?

let’s evaluate

1. Draw a line AB and take a point P, 4.5 cm away from it. Draw another line CD passing through
P and parallel to AB.
2. Draw any line l. Draw another line m parallel to l at a distance of 6.6 cm from it.

3. Construct a ∆ ABC in which BC = 5.5 cm, AB = 5.7 cm and AC = 6 cm.
4. Construct a ∆ ABC in which BC = 6.1 cm, AB = 5.7 cm and AC = 5.3 cm. Also draw the
perpendicular bisector of the side BC.
5. Construct an equilateral triangle each of whose side measures 6 cm. Measure each of its angle.

6. Construct a ∆ ABC in which AB = 6 cm, AC = 6.5 cm and ∠BAC = 60º.
7. Construct a ∆ PQR in which PQ = 5.2 cm, PR = 6.0 cm and ∠QPR = 45º.

8. Construct a triangle ABC in which AB = 6.2 cm and ∠A = ∠B = 75º.
9. Construct a triangle ABC in which BC = 6.5 cm, ∠C = 45º and ∠B = 60º.
10. Construct a right-angled triangle having hypotenuse 7 cm and one of its acute angles measuring
45º.

Thinking Skills

1. In the adjacent figure ∠1 = ∠2 and ∠3 = ∠2. Also RP bisects ∠CRQ. Prove that AB || CD.
2. Construct a right-angled triangle having base 5 cm and the A P Q B
longest side 7 cm. Measure its third side. What type of a triangle 3
is formed on the basis of its sides? 1
2
3. Construct an obtuse ∆ ABC with AB = 2.5 cm, BC = 3 cm and
CA = 5 cm. Construct a median to the side AC. C R D

4. Draw a ∆ XYZ with base YZ = 8 cm, ZX = 7 cm and XY = 5.5 cm. Draw an altitude
and a median from vertex X on YZ. Measure their lengths. Which is shorter and by how
much?

207