In the triangle ABC, the angle A is three times angle B, and angle C is 60 degrees. Find angle A.

90°

40°

80°

120°

Show Answer…

Correct Answer:90°

In the triangle ABC, the angle A is three times angle B, and angle C is 60 degrees. Find angle A.

A. 40°
B. 80°
C. 90°
D. 120°

Explanation:

Let angle B= x
then angle A= 3x
also given angle C=60°
as sum of angles of triangle equal to 180° i.e.
∠A + ∠B + ∠C = 180°
⇒ 3x + x + 60° = 180°
⇒ 4x = 180° – 60°
⇒ 4x = 120°
⇒ (angle B) x = 120°/4
⇒ x = 30°
Angle A = 3x = 3(30) ⇒ 90°