已知sina=根号5/5,则sin^4 a-cos^4 a [急!]

已知sina=根号5/5,则sin^4 a-cos^4 a [急!] 已知sina=根号5/5,则sin^4-cos^4a得值? 已知sin(a+π/3)+sina=-(4倍根号下3)/5,-π/2 已知sin(a+π/3)+sina=-4根号3/5,-π/2 已知sin(a+pie/3)+sina=-4根号3/5,-pie/2 已知sin(a+π/3)+sina=-4根号3/5 -π/2 已知sina=根号5/5,则sin^4a-cos^4a的值为_____, 已知cos(a+兀/6)-sina=4/5根号3,则sin(a-兀/6)= 已知cos(a-π/6）+sina=4根号下3/5,则sin(a+7π/6)=? 已知cos(a-π/6)+sina=(4*根号3)/5,则sin(a+7π/6)的值是( ) 已知sina=5分之根号5,则cosa+sina分之cosa-sina+cosa-sina分之cosa+sina= 已知sina=根号5/5,则sin四次方a-cons四次方a是值为 已知sina-cosa=根号2/2,则sin^4a+cos^4a= 已知sina+cosa=根号2/2,则sin^4a+cos^4a 已知sin（a＋派/3）+sina＝-(4根号3)/5,－派/2 已知sin（a＋派/3）+sina＝-(4根号3)/5,－派/2 (T=派)1.已知a属于[5T/2,7T/2],则根号下(1+sina)+根号下(1-sina)2.若1/cosa-1/sina=1 则 sin(2a)= 已知cotβ=根号5,sina/sinβ=sin(a+β),求cot(a+β).