Question

Zpls help me it worth 100 points

Answer 1

`\boxed{sin^(2)\alpha +cos^(2)\alpha =1}`
`\boxed{a^(2) - b^(2) = (a-b)(a+b)}`

`(cos^(2) \alpha )/(sin\alpha -1) = (1 - sin^(2) \alpha )/(sin\alpha -1) = ((1 - sin \alpha)(1 + sin \alpha) )/(sin\alpha -1) =\\`

`= - ((sin \alpha - 1)(1 + sin \alpha) )/(sin\alpha -1) = - (1 + sin\alpha)`

Answer 2

`(cos^2A)/(sin A - 1)`

=
`(1 - sin^2A)/(sinA-1)`