In an isosceles triangle, if the unequal angle is twice

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In an isosceles triangle, if the unequal angle is twice the sum of the equal angles, then each equal angle is

1. 120°
2. 60°
3. 30°
4. 90°

Correct Option: C

We draw a figure of an isosceles triangle ABC ,

Given that , ∠ B = ∠ C
∴ ∠ A = 2(∠ B + ∠ C)
⇒ ∠ A = 4∠ C
we know that , ∠ A + ∠ B + ∠ C = 180°
∴ 4∠ C + ∠ C + ∠ C = 180°
⇒ 6∠ C = 180°
⇒ ∠ C = 30°