Question

does (sinx)(tanxcosx-cotxcosx) equal -cos(2x)?

Answer 1

try substituting (sinx / cosx) for tanx and (cos x / sinx) for cotx and simplify

Answer 2

then use the identity cos 2x = cos^2 x - sin^2 x

Answer 3

(sinx)[(sinx/cosx)-cosx/sinx)(cosx) is that what you mean?

Answer 4

sorry (sinx)[(sinx/cosx)(-cosx/sinx)(cosx)

Answer 5

not quite its

sinx sinx cos x - cos x cosx sin x
--- ----
cosx sinx

- can you see that cos x and sin x cancel out?

Answer 6

i see what i did wrong but where do they cancel out?