Trig Identities Question NEED HELP

1. Jan 24, 2010

darrenc

How do I prove that

(1+sin2x) = (cosx)
(cosx + sinx) (cosx - sinx)

Last edited: Jan 24, 2010
2. Jan 24, 2010

Staff: Mentor

I can't tell what you need to prove, since what you have written is ambiguous. Put parentheses around the terms in each numerator and in each denominator.

Do you know any double angle identities?

3. Jan 24, 2010

darrenc

I know double angle identities such as

sin2x = 2sinxcosx and the three cos2x ones but i cant get anything to work

I've got all the formulas but i dont know how to use them to make it work

4. Jan 24, 2010

Hockeystar

Dude, i got pissed off at this same question yesterday. The key is 1 +2sinxcosx is a perfect square!!!