为什么sinx/2+√3cosx/2=2sin(x/2+π/3)?

问题描述:

为什么sinx/2+√3cosx/2=2sin(x/2+π/3)?

sin(x/2)+√3cos(x/2)
=2*[1/2*sin(x/2)+√3/2*cos(x/2)]
=2[sin(x/2)cosπ/3+cos(x/2)sinπ/3]
=2sin(x/2+π/3)