- Prove that
$$\sec ^ { 2 } x - \operatorname { cosec } ^ { 2 } x \equiv \tan ^ { 2 } x - \cot ^ { 2 } x$$
(ii) Given that
$$y = \arccos x , \quad - 1 \leqslant x \leqslant 1 \text { and } 0 \leqslant y \leqslant \pi ,$$
- express arcsin \(x\) in terms of \(y\).
- Hence evaluate \(\arccos x + \arcsin x\). Give your answer in terms of \(\pi\).