2sin^2+cos^X/sin^2+cos^2=2tan^2X+1/tan^2X+1 这个是怎么换算过来的

已知tan=2,求(cos x+sin x)/(cos x-sin x)+sin^2x 化简(sin x+cos x-1)(sin x-cos x+1)/sin 2x 化简 cos^2(x)*sin^2(x)-sin^2(x) 化简 cos^(2)(x)*sin^(2)(x)-sin^(2)(x) 化简sin^4x-sin^2x+cos^2x 化简:sin^4 x-sin^2 x+cos^2 x 化简[1-(sin^4x-sin^2cos^2x+cos^4x)/(sin^2)]+3sin^2x (sin^2x+cos^2x )(sin^2x-cos^2x)怎么得sin^2x-cos^2x? 已知sin(x)+3cos(x)=2,求sin(x)-cos(x)/sin(x)+cos(x)=? .若f(x)=sinα－cosx,则f′(α)等于 A.sinα B.cosα C.sinα+cosα D.2sinα sin(x/2)cos(x/2)= 化简sin^4x+cos^2x sin[cos^2(x^3+x)],求导 y=(sin x + COS x)^2 化简(sin^2x-cos^4x+cos^2x-sin^4x)/(sin^2x-cos^6x+cos^2x-sin^6x) ∫sin(x) cos^2(x)dx 2sin@+cos@等于? cos^2+2sinxcosx+sin^2x