1+sin(a-360)cos(a-270)-2cos^2 a
1+sin(a-360)cos(a-270)-2cos^2 a
证明Cos^A-Sin^A=1-2Sin^A=2Cos^A-1=cos^a-sin^a
化简:sin 2a/(1+cos 2a) * cos a/(1+cos a)
化简 1-sin^4a-cos^4a/cos^2a-cos^4a
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
化简Sin A + Sin 2A / 1+cos A +
sin(180+a)+cos(90+a)=-a则cos(270-a)+2sin(360-a)=?
求证:tan a/2=(1-cos)/sin a=sin a/(cos a+1)
tan a/2=sin/1+cos a=1-cos a/sin a
已知 sin a-cos a=1/2,则 sin^3 a-cos^3 a
若sin^4a/sin^2b+cos^4a/cos^2b=1,证明sin^4b/sin^2a+cos^4b/cos^2a