Question
Prove the following :
Solution
Put x = sin θ
∴L.H.S. = 3 sin –1x = 3 sin–1(sin θ) = 3 θ
R.H.S. = sin–1(3 x – 4 x3)
= sin–1(3 sin θ – 4 sin3 θ)
= sin–1(sin 3 θ) = 3 θ
∴L.H.S. = R.H.S.
