Question

Please Help! The expression sinx (cosx cotx - sinx) simplifies to_______?

1) cot^2x-sin^2x

2) 1

3) cos(2x)

Answer 1

3 is correct cos*2x-sin*2x=cos2x

Answer 2

\[cosx cotx - sinx = cosx * \cos x/\sin x - \sin x = (\cos ^2 x - \sin^2x)/\sin x = \cos 2x/\sin x\]
\[answer = \cos 2x/\sin x*\sin x = \cos 2x\]