证明cos^4A=1/4+cos2A+1/4cos^2A
证明sin(4A)sin(2A)(1-cos(2A)) cos(4A)cos(2A)(1 cos(2A))=cos(2A
tan(π/4+a)=1/2 求(sin2a-cos平方a)÷(1+cos2a)
化简[cos(4a-π/2)*sin(π/2-a)*cos2a]/[(1+cos2a)(1+cos4a)*cosa
化简[2sin2a/(1+cos2a)]*(cos^2a/cos2a)
求证sin^4a-cos^4a=-cos2a
三角比:[cos(4a-PAI/2)*sin(PAI/2-2a)]/[(1+cos2a)*(1+cos4a)]
cos2A+cos(4π/3-2A)化简,
若sin^4a/sin^2b+cos^4a/cos^2b=1,证明sin^4b/sin^2a+cos^4b/cos^2a
已知cos2a=(1/4),求cos^4a+sin^4+sin^2acos^2a的值
tan(pi/4+a)=0.5 (1)求tana(2)求sin2a-cos^2a/1+cos2a
求证:sin a (1+cos2a)=sin a cos a
证明:cos^4 a-sin^4 a=cos^2 a(1-tan a)(1+ tan a)