已知cos^4a/cos^2β+sin^4a/sin2^β=1 求证cos^4β/cos^2a+sin^4β/sin^2

若2sin(π/4+a）=sinθ+cosθ,2sin^2β=sin2θ,求证sin2a+(1/2)cos2β=0. 若2sin(π/4+a）=sinθ+cosθ,2sin^2β=sin2θ,求证sin2a+(1/2)cos2β=0 若sin^4a/sin^2b+cos^4a/cos^2b=1,证明sin^4b/sin^2a+cos^4b/cos^2a 化简(1-sin^6 a-cos^6 a)/(cos^2 a-cos^4 a)== 证明sin(4A)sin(2A)(1-cos(2A)) cos(4A)cos(2A)(1 cos(2A))=cos(2A 已知tan a=-1/3,求4sin a-2cos a/5cos a+3sin a= 求证sin^4a+cos^4a=1-2sin²acos²a 已知cosa=1/4,求sin(2π+a)cos(-π+a)/cos(-a)tana 化简 1-sin^4a-cos^4a/cos^2a-cos^4a 已知(4sin a－2cos a)／(5cos a +3sin a)=6/11,求cos＾4 a－sin＾4 a 已知sin a-2cos a=0 求4sin^2 a-3sin a x cos a-5cos^2 a的值 若sin(π/4+α)=sinθ+cosθ,2sin^2β=sin2θ,求证：sin2θ+2cos2β=3