# identity

• Jul 24th 2010, 06:35 AM
Stuck Man
identity
((sin x)^2 - (cos x)^2) / (sin x- cos x) = sin x + cos x

I want to change the LHS only.
• Jul 24th 2010, 06:50 AM
Failure
Quote:

Originally Posted by Stuck Man
((sin x)^2 - (cos x)^2) / (sin x- cos x) = sin x + cos x

I want to change the LHS only.

Remember $a^2-b^2=(a+b)(a-b)$? If so, apply that to the LHS, then cancel the common factor $a-b$ of numerator and denominator.