Question

1. \cot^{2}u - \csc^{2}u

Explanation:

Step1: Recall the Pythagorean identity

We know that \(1+\cot^{2}u=\csc^{2}u\).

Step2: Rearrange the identity

From \(1 + \cot^{2}u=\csc^{2}u\), we can get \(\cot^{2}u-\csc^{2}u=- 1\).

Answer:

\(-1\)