求2(cosπ/3sinx+sinπ/3cosx) =2 sin(x+π/3) 中2 sin(x+π/3)的得来?
问题描述:
求2(cosπ/3sinx+sinπ/3cosx) =2 sin(x+π/3) 中2 sin(x+π/3)的得来?
答
因为
sinacosb+cosasinb
=sin(a+b)
两角和的正弦公式.