[SOLVED] Proving two sides of equation for triangles 1. The problem statement, all variables and given/known data In angle ABC, which is an isosceles triangle with <B = <C, show that 2cot(a) = tan(b) = cot(b) 2. Relevant equations tan2a = 2tana / 1 - tan^2 a tan (x - y) = tanx - tany / 1 + tanx tany 3. The attempt at a solution Since it is isosceles, that means two sides are equal, therefore, <A = 180 - 2B 2cot(A) = 2cot (180 - 2B) = 1 / 2tan(180 - 2B) = 1 / 2(tan180 - tan2B / 1 + tan180 tan2B) = 1 / 2(-tan2B) = 1 / -2tan2B) = 1 / -2(2tanB / 1 - tan^2 B) After this, I get confused. Can someone please tell me if I am doing this right? Please help. Thanks.