Question

in ABC ab = ac if angle c =70 degree find angle A

Answer 1

In triangle ABC AB=AC and angle c is 70 degrees 

as AB and AC are equal angles opposite to equal sides AB AND AC;; 

Angle B= Angle C = 70

Now we know that Angle b = 70 angle C is 70 
so angle A will be= 180-ANGLE B+ANGLE C=180-140=40

Answer 2

As ab=ac, Therefore ABC is a isoceles triangle. C=70
Therefore,B=70(ab=ac)
By angle sum property of triangle,
A+B+C=180
A+70+70=180
Hence,A=40