This question already has an answer here:
$\cot x=\sin x \sin(\pi/2 -x) + \cos^2x \cot x$
I'm having difficulty with figuring out how to prove trigonometric identities. I know that in order to do these you need to use the trig ratios reciprocal, quotient identities and compound angle formulas. If someone could guide me through these kind of questions. That would be really appreciated!