Consider the following expressions as right hand sides of identities. Find a suitable left hand side from (A-D) that completes each identity.

 1. $\displaystyle{\frac{\sin(x)+\cos(x)}{\sin(x)}}$
 2. $(\csc(x)-\cot(x))(\csc(x)+\cot(x))$
 3. $\displaystyle{\frac{\cos(x)-\sec(x)}{\sec(x)}}$
 4. $\displaystyle{\frac{\sin(x)}{\cos(x)}+\frac{\cos(x)}{\sin(x)}}$

Answers:

A. $1+\cot(x)$
B. $-\sin^2(x)$
C. $1$
D. $\displaystyle{\frac{1}{\sin(x)\cos(x)}}$