If cosA is not equal to 1, then sin^2A/(1-cosA) =

A) 1 + cosA

B) cosA

C) 1-cosA

D) 1

E) cosA -1

Remember the mother of all trig identities:

The minute you see that in there you should be thinking of that identity. Rearrange it so that you can do some substituting:

Now here’s what you’re working with:

Now let’s get nuts and factor the difference of two squares up there in the numerator:

Of course, you can simplify that to just