已知:sina^2/sinβ^2 +cosa^2cosy^2=1 , 求证 tana^2/tanβ^2=siny^2a,β均为锐角,且cosacosβ-sinasinβ=sinacosβ-cosasinβ,则tana= ?

已知(sina+cosa)/(sina-cosa)=3 则2sin'a+(sina-cosa)'=? 证明sin^2a+sin^2β+1>sina*cosa+sina+sinβ 已知sina=1/2计算sin(5派-a) 已知sin(pai-a)-2cosa=0若sina 已知sina=3/2sin^2α+sin^2β,则函数y=sin^2α+sin^2β的值域为1 已知cosB = cos θ*sinA,cosC = sinθ*sinA.θ为已知角.则sin^2 A + sin^2 B +sin^2C等于多少? 已知cos(a+β)cosa+sin(a+β)sina=--0.2,求sin(3π/2-β) 已知sina+sinβ=√2/2求cosa+cosβ的范围 sin(2a+β)/sina-2cos(a+β)=sinβ/sina 已知tana=-3,求sina+2cosa/cosa-3sina和sin^2a-sinacosa 已知sina-2sina=0,求sin2a-cos2a/1+sin平方a 已知sin a+cos a=1/2 sina*cosa=?cos a/sina+sina/cosa=? 已知3SIN^2A+2SIN^2B=5SINA,求SIN^2A+SIN^2B范围 1.已知cosB=cosθ*sinA,cosC=sinθ*sinA,求证sin^2 A+sin^2 B +sin^2 C=2 若3sin²a+sin²β=2sina,求2sina+sin²β 已知sinA=1/5,求2sin(A+B)cosA-sin(2A+B) 已知tana=2,则(sin^3a+cosa)/(sin^3a+sina)的值为? 已知sina+sin²a=1则cos四次方β+3sin²β-2sinβ+1=急