Prove each of the following identities:
Consider L.H.S. = 
= 
= 
= 
= 
= sin θ (cos3 θ) + cos θ (sin3 θ)
= sin θ cos θ (cos2 θ + sin2 θ)
= sin θ cos θ
= R.H.S.
Hence, proved.
16
Prove each of the following identities:
Consider L.H.S. =
=
=
=
=
= sin θ (cos3 θ) + cos θ (sin3 θ)
= sin θ cos θ (cos2 θ + sin2 θ)
= sin θ cos θ
= R.H.S.
Hence, proved.