geometry

 

In isosceles triangle ABC, angle A is 40 degrees.  Find all possible values of angle B.     

 

If A (40^o) is the apex angle, then B and C are (1/2)(180^o – 40^o)  =  70^o     

 

If B is the apex angle, then A (40^o) and C are 40^o and B is 180^o – 80^o  =  100^o     

 

If C is the apex angle, then A (40^o) and B are the equal base angles, and they =  40^o     

_.