Question

How to proof that cotan x - cos x/cos x = cos ^2x/1+sin x ?

Answer 1

Assuming that the left hand side reads
`{cot x - cos x}/cot x`, the proof is:

`{cot x - cos x}/cot x = 1-cos x/cot x = 1-sin x`
`= (1-sin x) times {1+sin x}/{1+sin x}= {1-sin^2 x}/{1+sin x} = cos^2 x/{1+sin x}`