Question

化简 sin(θ+75°)+cos(θ+45°)+cos(θ+15°)

Answer 1

sin(a+75°)+cos(a+45°)+cos(a+15°) =sin(a+15+60)+cos(a+15+30)+cos(a+15) =sin(a+15)cos60+cos(a+15)sin60+cos(a+15)cos30-sin(a+15)sin30+cos(a+15) =2sin60cos(a+15)+cos(a+15) =(1+√3)cos(a+15)