1. ## trig identities #2

(sin^2(a)+2cos(a)-1)/(2+cos(a)-cos^2(a))

2. ## Re: trig identities

Originally Posted by ahmedb
(sin^2(a)+2cos(a)-1)/(2+cos(a)-cos^2(a))
Start by using \displaystyle \begin{align*} \sin^2{a} \equiv 1 - \cos^2{a} \end{align*} to convert it to something only in terms of cosines.