Answer each of the following.Consider the expression $\tan \left(\frac{\pi}{2}+x\right)$
(a) Why can't we use the identity for $\tan (A+B)$ to express it as a function of $x$ alone?
(b) Use the identity $\tan \theta=\frac{\sin \theta}{\cos \theta}$ to rewrite the expression in terms of sine and cosine.
(c) Use the result of part (b) to show that
$$
\tan \left(\frac{\pi}{2}+x\right)=-\cot x
$$