Question

Prove that 

(i) sin(45° + θ) – sin(45° – θ) = √2sin θ.

(ii) sin(30° + θ) + cos(60° + θ) = cos θ.

Answer 1

(i) sin(45° + θ) – sin(45° – θ) = √2sin θ

sin(45° + θ) = sin 45° cos θ + cos 45° sin θ

(ii) sin(30° + θ) + cos(60° + θ) = cos θ

sin(30° + θ) = sin 30° cos θ + cos 30° sin θ