求证TAN3X/2-TANX/2=2SINX/(COSX加COS2X)
求证:tg(3x/2)-tg(x/2)=2sinx/(cosx+cos2x) 证明: tg(3x/2)-tg(x/2) =[sin(3x/2)/cos(3x/2)]-[sin(x/2)/cos(x/2)] =[sin(3x/2)*cos(x/2)-sin(x/2)*cos(3x/2)]/cos(3x/2)*cos(x/2) =sin[(3x/2)-(x/2)]/(1/2){[cos[(3x/2)+(x/2)]+cos[(3x/2)-(x/2)]} =sinx/[(1/2)(cos2x+cosx)] =2sinx/(cos2x+cosx) 得证
答:1.tan(3x/2)-tan(x/2)=sin(3x/2)/cos(3x/2)-sin(x/2)/cos(x/2) =[sin(3x/2)cos(x/2)-c...详情>>
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