Q25 of 123 Page 9

Prove the following identities:
sin 3x + sin 2x – sin x = 4 sin x cos

Proof:

Take LHS:

sin 3x + sin 2x – sin x

Identities used:

sin 2x = 2 sin x cos x

Therefore,

= RHS

Hence Proved

Prove the following identities:

cot² x – tan² x = 4 cot 2x cosec 2x

Prove the following identities:

cos 4x – cos 4α = 8(cos x – cos α) (cos x + cos α) (cos x – sin α) (cos x + sin α)

Prove that:

Prove the following identities:sin 3x + sin 2x – sin x = 4 sin x cos