Question

In a triangle , if two angles are 60°, third angle is

• A. 120°
• B. 150°
• C. 90°
• D. 60°

Answer 1

The correct option is D 60°

Let us consider in a triangle LMN,
∠L = ∠N = 60°

Using angle sum properties of triangles.
The sum of ∠L, ∠M and ∠N of a triangle LMN equals to 180°.
i.e,
∠L + ∠M + ∠N = 180°
60° + ∠M + 60° = 180°
⇒∠M = 180°- 120°
⇒∠M = 60°