[질문] 미적분공식중에서삼각함수합성 공식좀

sin(a)cos(b)=1/2{sin(a+b)+sin(a-b)}cos(a)sin(b)=1/2{sin(a+b)-sin(a-b)}cos(a)cos(b)=1/2{cos(a+b)+cos(a-b)}sin(a)sin(b)=-1/2{cos(a+b)-cos(a-b)}입니다.