Question

Please give some very difficult questions of trigonometry to solve

Answer 1

cos 42°×cos 23°×cos 30°×cos 48°×cos 67°

Answer 2

1.prove that xsin^3theta+ycos^3theta=sin theta.cos theta

2.if 2 sin x/1+cosx+sinx=t

Then find the value of 1-cosx+sinx/1+sinx