Question:
In a ΔABC, if ∠A = 120° and AB = AC. Find ∠B and ∠C.
Solution:
Consider a ΔABC
Given Mat ∠A = 120° and AB = AC and given to find ∠B and ∠C.
We can observe that ΔABC is an isosceles triangle since AB = AC
∠B = ∠C (i)
[Angles opposite to equal sides are equal]
We know that sum of angles in a triangle is equal to 180°
⟹ ∠A + ∠B + ∠C = 180° [From (i)]
⟹ ∠A + ∠B + ∠B = 180°
⟹ 120° + 2∠B = 180°
⟹ 2∠B = 180° - 120°
⟹ ∠B = ∠C = 30°
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