Who wants to help me with trig identities?!

Good times, I know. I have my precalc final today and I am surely going to bomb it unless I can figure stupid stuff like this out.

Below is the answer to one of my practice problems (in comic sans!) - I don’t get the second step (the first equation with no left side)

How does 1+cos^2(x) turn into sin^2x + cos^2x

Bleeehhhh