Question

I don't know what else to do, help me establishing identities.

Answer 1

\[\cot ^{2} \frac{ u }{ 2 }= \frac{ \csc u + \cot u }{ \csc u-\cot u }\]

Answer 2

what i did : \[\cot \frac{ u }{ 2 }* \cot \frac{ u }{ 2 } \]
\[\frac{ 1 }{ \tan \frac{ u }{ 2 }} * \frac{ 1 }{ \tan \frac{ u }{ 2 } }\]
\[\frac{ 1 }{ \frac{ \sin u }{ 1+\cos u } } * \frac{ 1 }{ \frac{ \sin u }{ 1+\cos u } }\]

Answer 3

what else should I do or what did I do wrong?