LINES & ANGLES grade 9

If one angle of a triangle is equal to the sum of the other two angles, then the triangle is

• (A) an isosceles triangle

• (B) an obtuse triangle

• (C) an equilateral triangle

• (D) a right triangle

The angles of a triangle are in the ratio 5 : 3 : 7. The triangle is

• (A) an acute angled triangle

• (B) an obtuse angled triangle

• (C) a right triangle

• (D) an isosceles triangle

If one of the angles of a triangle is 130°, then the angle between the bisectors of the other two angles can be

• (A) 50°

• (B) 65°

• (C) 145°

• (D) 155°

Angles of a triangle are in the ratio 2 : 4 : 3. The smallest angle of the triangle is

• (A) 60°

• (B) 40°

• (C) 80°

• (D) 20°

Can a triangle have all angles less than 60°?

• yes

• no

Can a triangle have two obtuse angles?

• yes

• no

How many triangles can be drawn having its angles as 45°, 64° and 72°.

• one

• two

• infinite

• none

How many triangles can be drawn having its angles as 53°, 64° and 63°?

• one

• two

• infinite

• none

Two adjacent angles are equal. Is it necessary that each of these angles will be a right angle?

• yes

• no

If one of the angles formed by two intersecting lines is a right angle, what can you say about the other three angles?

• Each will be 60⁰

• Each will be a right angle