To Prove: Taking LHS, [∵ cos 2x = cos2x – sin2x]Using, (a2 – b2) = (a – b)(a + b)= cos x + sin x= RHS∴ LHS = RHSHence Proved

Q5 of 113 Page 575

Prove that

To Prove:

Taking LHS,

[∵ cos 2x = cos²x – sin²x]

Using, (a² – b²) = (a – b)(a + b)

= cos x + sin x

= RHS

∴ LHS = RHS

Hence Proved

If , find the value of sin 3x.

If , find the value of cos 3x.

Prove that