1+cos(2x)/sin(2x)=3/4,求tan(x/2)

已知sin(x)+3cos(x)=2,求sin(x)-cos(x)/sin(x)+cos(x)=? 2sin^2x - 5sin x cos x=3 cos^2x,求X, 求证(3-sin^4 x-cos^4 x)/2cos^2 x=1+tan^2 x+sin^2 x Sin x-sin y=2/3 cos x-cos y=1/2 求cos(x-y) 怎么证明2(1-sin x)(1+cos x)=(1-sin x+cos x)^2 化简y=sin^2(x)+2sin(x)cos(x)+3cos^2(x) 化简 1/2cos x-根号3/2sin x 根3sin x+cos x 证明sin^2(x)+cos^2(x+30)+sin(x)cos(x+30)=3/4 化简[1-(sin^4x-sin^2cos^2x+cos^4x)/(sin^2)]+3sin^2x 求证（cos^2 x-sin^2 x)(cos^4 x+sin^4 x)+1/4 sin 2x sin 4x=cos 2x sin^3 x -cos^3 x sin^3 x -cos^3 x =(sin x -cos x )(sin^2 x +sin x*cos x +cos^2 x )问下这个是个公式还是什么?怎么样算出来的? 证明1-sin^6x-cos^2x/1-sin^4x-cos^4x=3/2 求证：1-cos^4x-sin^4x/1-cos^6x-sin^6x=2/3 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 证明成立：[cos(3x)-sin(3x)]/(cosx+sinx)=1-2sin(2x). 若sin x/2 - cos x/2 = 1/3,则sin x=? 若sin x/2-cos x/2=1/3,则sin x=