- #1

rum2563

- 89

- 1

**[SOLVED] Proving two sides of equation for triangles**

## Homework Statement

In angle ABC, which is an isosceles triangle with <B = <C, show that

2cot(a) = tan(b) = cot(b)

## Homework Equations

tan2a = 2tana / 1 - tan^2 a

tan (x - y) = tanx - tany / 1 + tanx tany

## 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.