Question

In triangle ABC,AB=AC.if angle B =80,find the measure of angle A

Answer 1

In triangle ABC ,
side AB = side AC...
therefore,
angle ABC = angle ACB........(1)
( the sum of the triangle is 180.)
therefore,
angle A + angle B + angle C = 180
angle A + 2 angle B. = 180......from (1)
angle A + 2 * 80. = 180
angle A + 160. =180
angle A = 180 -160
= 20
angle A = 20 degree...
hence, the angle A is 20 ..

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