In an isosceles triangle ∆ ABC, AB = AC and ∠A

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In an isosceles triangle ∆ ABC, AB = AC and ∠A = 80°. The bisector of∠B and ∠ C meet at D. The ∠BDC is equal to

1. 90°
2. 100°
3. 130°
4. 80°

Correct Option: C

As per the given in question , we draw a figure of an isosceles triangle ABC

Given that , AB = AC
∴ ∠ABC = ∠ACB
∠A = 80°
∴ ∠B + ∠C = 180° – 80° = 100°
∴ ∠B = 100 ÷ 2 = 50° = ∠C
∴ ∠DBC = ∠DCB = 50 ÷ 2 = 25°
∴ ∠BDC = 180° – (∠DBC + ∠DCB) = 180° – 50° = 130°