sin^4a-cos^4a=sin^2-cos^2a
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
(cos a)^4+(sin a)^2*(sin a)^2+(sin a)^2=?
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
已知a(-0,兀且2SIN A-SIN ACOS A-3COS A=0求SIN(+兀/4)/SIN 2A+COS 2A+
已知:tan A=2,求:(2sin A-2cos A)/(4sin A-9cos A) 、
已知tan a=2,求:(4*sin a-2*cos a)/(5*sin a+3*cos a)的值
已知tan a=-1/3,求4sin a-2cos a/5cos a+3sin a=
化简 1-sin^4a-cos^4a/cos^2a-cos^4a
证明Cos^A-Sin^A=1-2Sin^A=2Cos^A-1=cos^a-sin^a