Question

Verify the identities
(1+sinx)(1-sinx)=cos^2x

Answer 1

\[(a+b)(a-b) = a ^{2}-b ^{2}\]
Multiply it out and then use the pythagorean identity:
\[\sin ^{2}x + \cos ^{2}x = 1\]

Answer 2

Multiply out the left side. It's the product of a sum and a difference. What do you get?