Applying the cosine addition and sine addition formulas proves the cofunction, add pi, and supplementary angle identities. Using the formulas, we see that sin(pi/2-x) = cos(x), cos(pi/2-x) = sin(x); that sin(x + pi) = -sin(x), cos(x + pi) = -cos(x); and that sin(pi-x) = sin(x), cos( -x) = -cos(x). The formulas also give the tangent of a difference formula, for tan(alpha-beta).

I was wondering how I could prove this algebraically. I know I have to start off by converting -tanx to (-sinx/cosx), but I do not know where to go from there.

May 29th, 2015

Can you show this algebraically?

May 29th, 2015

Studypool's Notebank makes it easy to buy and sell old notes, study guides, reviews, etc.