y'=4sin(2x+π/3)cos(2x+π/3) 化简 y'=2sin(4x+2π/3).怎么化简的?

问题描述:

y'=4sin(2x+π/3)cos(2x+π/3) 化简 y'=2sin(4x+2π/3).怎么化简的?

三角函数倍角公式为:
sin2x=2sinxcosx
所以:
y'=4sin(2x+π/3)cos(2x+π/3)
=2sin2(2x+π/3)
=2sin(4x+2π/3)