Question

sin20°.sin40°.sin80°.sin160°=?

Answer 1

Correct your question

There is a mistake

I think it should be sin60° in place of sin160°

On assuming as sin60

Since sin 60= root3/2

=> root3/2 [ sin 20 . Sin 40 . Sin 80]

=> root3/2 [ sin 20 . Sin (60-20) . Sin (60+ 20) ]

We know that sin x . Sin (60-x) . Sin (60+ x) = ¼ sin 3x

Therefore, root3/2 [ ¼ sin60]

Root 3/2 . ¼ . root 3/2

=> 3/16.