1. ## Trigonometry

Prove the following identity:

2. ## Re: Trigonometry

have you attempted anything yourself yet? I would recommended factoring it to start.

3. ## Re: Trigonometry

The identity $1+tan^2A=sec^2A$ will also be useful

4. ## Re: Trigonometry

The given expression is 1-( Sec2A-Tan2A)2=1-12=0

5. ## Re: Trigonometry

LHS = 1 - ( sec^4A - 2 sec^2 A tan^2 A + tan^4 A )
= 1 - ( sec ^2 A - tan ^2 A )^2 = 1 - 1 = 0 = RHS