Question

How do you verify `csc ^4 -2csc ^2 x +1 = cot^4 x`?

Answer 1

`sin^2 A + cos^2 A = 1`
Divide by sin^2 A:
`1 + cot^2 A = csc^2 A`

`csc^4 x - 2csc^2 x + 1 = (csc^2 x - 1)^2 = (cot^2 x)^2 = cot^4 x`