Question

Simplify: (Sin^2x)/(Sec^2x-1)

Answer 1

(sin^2 x)/(sec^2 x - 1)

(sin^2 x)/(tan^2 x)
(sin^2 x)/(sin^2 x/cos^2 x)
(sin^2 x) * (cos^2 x/sin^2 x)
cos^2 x

therefore,
(sin^2 x)/(sec^2 x - 1) = cos^2 x