Question

In the given figure,AB=AC and angle A=40,then find angle c.

Answer 1

After seeing the figure we can say that it is an isosceles triangle

In an isosceles triangle both sides are equal and their opposite angles are also equal

Therefore angle B= angle C

A+B+C=180(angle sum theorem)

40+ B+C = 180

B+ C = 140

B+B=140( both angles are equal as proved above)

2B=140

B=140/2

B=70

AS WE KNEW B=C

C = 70

Answer 2

as we now that as two sides
AB=AC
we can say that it is issoselss triangle
so base angles are equal
then
let us consider angle B=C=x
so from question angle A=40
by sum of angles of triangle
B+C+A=180
x+x+40=180
2x=180-40
2x=140
x=140/2
x=70
hence angle C=70