sin(x+105°)cos(x-15°)-cos - 知识问答

sin(x+105°)cos(x-15°)-cos(x+105°)sin(x-15°)

3个回答

根据sin(A-B)=sinAcosB-cosAsinB
sin(x+105°)cos(x-15°)-cos(x+105°)sin(x-15°
=sin(x+105°-x+15°)
=sin120°
=sin60°
=二分之根号三

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