Question

Evaluate cos48°.cos42°-sin 48°.sin42°

Answer 1

Step-by-step explanation:

cos48°=0.6691

cos42°.7431

sin48°=0.7431

sin42°=0.6691

let X be 48°

and cos(X)°=sin(90-x)°

and sin (X)=cos(90-x)°

so

cos48°.cos42°-sin48°.sin42°=0