In a ∆ABC, if AB=AC and A=70°, find B and C.

Given that


AB = AC and A = 70°


To find: B and C


AB = AC and also A = 70°


As two sides of triangle are equal, we say that ∆ABC is isosceles triangle.


Hence by the property of isosceles triangle, we know that base angles are also equal.


ie. we state that B = C. …(1)


Now,


Sum of all angles in any triangle = 180°


A + B + C = 180°


Hence,


70° + B + C = 180°


2 B = 180° - 70° …from (1)


2B= 110°


B = 55°


Therefore, our base angles, B and C, are 55° each.


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