Question

In triangle ABC, the measure of angle A is 40°. 1. Give possible measures for angles B and C if triangle ABC is isosceles. 2. Give possible measures for angles B and C if triangle ABC is right.

Answer 1

1. An isosceles triangle has two angles that are equal

so if angle A is 40°

Let the other two angles be 2x

2x + 40 = 180° (sum of angle in a triangle)

solve for x

2x + 40° = 180°

subtract 40° from both-side of the equation

2x = 180° - 40°

2x = 140°

Divide both-side of the equation by 2

x = 70°

There the possible measures for;

angle B = 70°

angle C = 70°

2.

In a right-angle triangle,

One of the angle must be 90°

angle A=40°

Let angle B = 90°

we will now find angle C

40° + 90° + C = 180° (sum of angle in a triangle)

solve for C

130° + C = 180°

subtract 130° from both-side of the equation

C = 180° - 130°

C=50°

The possible value of;

angle B=90°

angle C = 50°