Answer
$\sin u+\cot u\cos u=\csc u$
Work Step by Step
$\sin u+\cot u\cos u$
Substitute $\cot u$ with $\dfrac{\cos u}{\sin u}$ and simplify:
$\sin u+(\dfrac{\cos u}{\sin u})(\cos u)=\sin u+\dfrac{\cos^{2}u}{\sin u}=...$
$...=\dfrac{\sin^{2}u+\cos^{2}u}{\sin u}=...$
Since $\sin^{2}u+\cos^{2}u=1$, this expression becomes:
$...=\dfrac{1}{\sin u}=\csc u$
