Sin72+cos222-sin12 Help my please

Question

Sin72+cos222-sin12
Help my please

Answer 1

... = sin(90°-18°) + cos(270°-48°) - sin(12°) = 
= cos(18°) - sin(48°) - sin(12°) = cos(18°) - (sin(48°) + sin(12°)) = 
= cos(18°) - 2*sin(30°)*cos(18°) = cos(18°)*(1 - 1) = 0