Question

Prove -1 - cos^2 x = sin^2 x​

Answer 1

sin^2(x) + cos^2(x) = 1

sin^2(x) = 1 - cos^2(x)

1 - cos^2(x) = sin^2(x)

- 1 - cos^2(x) = sin^2(x) is proven incorrect.