Formula: Using double angle formula: 2cos 2 x – 1 = 1 – 2 sin 2 x ∴ 1 + cos 2 x = 2cos 2 x 1 - cos 2 x = 2sin 2 x ∴ = = cotx Differentiating y with respect to x = - cosec 2 x

If , find .

Formula:

Using double angle formula:

2cos²x – 1

= 1 – 2 sin² x

∴1 + cos 2 x = 2cos²x

1 - cos 2 x = 2sin²x

∴

= cotx

Differentiating y with respect to x

- cosec² x