Question

One angle in a triangle is 100 degrees. The other two angles are congruent. What is the measure of one of the missing angles?

(A) 40°
(B) 80°
(C) 130°
(D) 140°

Answer 1

A

Explanation:

The sum of the 3 angles in a triangle = 180°

let x be the measure of the congruent angles, then

x + x + 100 = 180, that is

2x + 100 = 180 ( subtract 100 from both sides )

2x = 80 ( divide both sides by 2 )

x = 40

Thus the measure of one of the congruent angles is 40°