Verify That the Equation Is an Identity $$\cot ^ { 2 } \frac { u } { 2 } = \frac { \csc u + \cot u } { \csc u - \cot u }$$

Essay

Verify that the equation is an identity.
- $$\cot ^ { 2 } \frac { u } { 2 } = \frac { \csc u + \cot u } { \csc u - \cot u }$$