Question

sin theta minus 2 Sin cube theta bai 2 cos cube theta minus cos theta barabar 10 theta

Answer 1

Hope you can understand my handwriting.

Answer 2

for ease
let theta= A
L.H.S
= sin A - 2sin³ A / 2cos³A - cos A
= sin A(1 - 2sin²A) / cos A(2cos²A - 1)
= 1- 2sin² A= cos 2A and, 2cos² -1= cos 2A
= sin A (cos 2A) / cos A (cos 2A) =
= sin A / cos A = 10
= tan A = R.S.H