已知6(sina)^2+sinacosa-2(cosa)^2=0 a属于[TT/2,TT) 求sin(2a+TT/3)已知6(sina)^2+sinacosa-2(cosa)^2 a属于[TT/2,TT) 求sin(2a+TT/3)

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已知6(sina)^2+sinacosa-2(cosa)^2=0 a属于[TT/2,TT) 求sin(2a+TT/3)已知6(sina)^2+sinacosa-2(cosa)^2 a属于[TT/2,TT) 求sin(2a+TT/3)
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已知6(sina)^2+sinacosa-2(cosa)^2=0 a属于[TT/2,TT) 求sin(2a+TT/3)已知6(sina)^2+sinacosa-2(cosa)^2 a属于[TT/2,TT) 求sin(2a+TT/3)
已知6(sina)^2+sinacosa-2(cosa)^2=0 a属于[TT/2,TT) 求sin(2a+TT/3)
已知6(sina)^2+sinacosa-2(cosa)^2 a属于[TT/2,TT) 求sin(2a+TT/3)

已知6(sina)^2+sinacosa-2(cosa)^2=0 a属于[TT/2,TT) 求sin(2a+TT/3)已知6(sina)^2+sinacosa-2(cosa)^2 a属于[TT/2,TT) 求sin(2a+TT/3)
因式分解
(3sina+2cosa)(2sina-cosa)=0
sina/cosa=-2/3或1/2(舍)
(sina)^2/(cosa)^2=4/9
(sina)^2/[1-(sina)^2]=4/9
(sina)^2=4/5
sina=2/√5,cosa=-1/√5
sin2a=2*2/√5*(-1/√5)=-4/5
cos2a=1/5
sin(2a+TT/3)=(√3-4)/10