Question
In $\triangle\text{ABC, AB = AC}$ and $\angle\text{B}=50^{\circ}.$ Then, $\angle\text{A = } ?$

Answer

  1. 80°
    Solution:
    In $\triangle\text{ABC,}$
    $\text{AB = AC}$
    $\Rightarrow\angle\text{C}=\angle\text{B}$ (angles opposite to equal sides are equal)
    $\Rightarrow\angle\text{C}=50^{\circ}$
    Now, $\angle\text{A}+\angle\text{B}+\angle\text{C}=180^{\circ}$
    $\Rightarrow\angle\text{A}+50^{\circ}+50^{\circ}=180^{\circ}$
    $\Rightarrow\angle\text{A}=80^{\circ}$

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