sinA+sin(120-A)=3/2 求A度数

sinA+sin(120-A)=3/2 求A度数 已知(sina+cosa)/(sina-cosa)=3 则2sin'a+(sina-cosa)'=? 若3sin²a+sin²β=2sina,求2sina+sin²β sinA=3sin(2π/3-A) SINA=?sinA=3sin(2π/3-A) SINA=?答案是-3√3cosA sinA=x,sin(A/2)=? sin^2a=(sina)^2对吗 1- sin(2π/3 - a)/sina 已知3SIN^2A+2SIN^2B=5SINA,求SIN^2A+SIN^2B范围 若(sina+cosa)/(sina-cosa)=2,则sin(a-5派)*sin(3派/2-a)等于? 若(sina+cosa)/(sina-cosa)=2,则sin(a-5pai)*sin(3pai/2-a)等于? 设(sina)^2-sina-2(cosa)^2=0,求sin(a-3π/2) 已知tana=-3,求sina+2cosa/cosa-3sina和sin^2a-sinacosa 2sin²A-7sinA+3=0,求sinA得多少 sina=2cosa,求(1)3sina+2cosa(2)sin²a+sina×cosa+3 sina+sin(120°-a)=根号3,怎样得到sin(a+30°)=1 2sin60=sinA+sin(120-A)如何推出sin(A+30)=1? 证明：[sin(a-60)]^2+[sina]^2+[sin(a+60)]^2=3/2 证明sinA+sin(A+2π/3)+sin(A-2π/3)=0