Qus: In triangle ABC, if AB=BC and ∠B = 70°, ∠A will be:

Qusत्रिभुज ABC में, यदि AB=BC और ∠B = 70°, A का मान होगा:

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A. 70°
B. 110°
C. 55°
D. 130°

Solution

C. 55°

Explanation

Given,

AB = BC

Hence, ∠A=∠C

And ∠B = 70°

By angle sum property of triangle we know:

∠A+∠B+∠C = 180°

2∠A+∠B=180°

2∠A = 180-∠B = 180-70 = 110°

∠A = 55°