化简sin(x+120°)+sin(x+240°)

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化简sin(x+120°)+sin(x+240°)
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化简sin(x+120°)+sin(x+240°)
化简sin(x+120°)+sin(x+240°)

化简sin(x+120°)+sin(x+240°)
sin(x+120°)+sin(x+240°)
=sinx*cos(120)+cosx*sin(120)+sinx*cos(240)+cosx*sin(240)
=-0.5sinx+二分之根号三cosx-0.5sinx-二分之根号三cosx
=-sinx

sin(x+120°)+sin(x+240°)=sin(60°-x)+sin(-60°-x)=sin(60°-x)-sin(60°+x)=sin60°cosx-cos60°sinx-sin60°cosx-cos60°sinx=-sinx