If x and y are acute such that , prove that

Prove that

If θ and Φ lie in the first quadrant such that , find the values of

(i) sin (θ - Φ )

(ii) cos (θ - Φ)

(iii) tan (θ - Φ)

If x and y are acute angles such that , prove that .

If, where

, find the values of

(i) sin (x + y)

(ii) cos (x + y)

(iii) tan (x – y)