In , AB=AC and =50^ . Then =?. - Vidyadip

MCQ

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

A
40
B
50
C
130
D
80

✓

Answer

80
Solution:

$\text{AB = AC}$ and $\angle\text{B}=50^\circ$
therefore, $\angle\text{C}=50^\circ$ also [angles opposite to equal sides are equal]
$\angle\text{A}+\angle\text{B}+\angle\text{C} = 180^\circ$ [by angle sum property of a triangle]
$⇒\angle\text{A}+50^\circ+50^\circ=180^\circ$
$⇒\angle\text{A} = 80^\circ$

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