(2-cos^2x)(2+tan^2x)=(1+2tan^2x)(2-sin^2x)
证明(1-2sin x cos x )/(cos^2x-sin^2x)=(1-tan x)/(1+tan x)
证明1-tan^2x/1+tan^2x=cos^2x-sin^2x
已知tan=2,求(cos x+sin x)/(cos x-sin x)+sin^2x
证(1/sin^2x)+(1/cos^2x)-(1/tan^2x)=2+tan^2x
求证 (1—tan^2X)/(1+tan^2X)=cos^2X—sin^2X
求极限x趋于0时(1-cos(x/2))x / (tan x-sin x)
tan(x+y)tan(x-y)=sin^2x-sin^2y/cos^2x-sin^2y 顺便问一下. tan,sin,
证明1/sin^x+1/cos^2x-1/tanx^2x=2+tan^2
化简sin(派-x)+sin(派+x)-cos(-x)+cos(2派-x)-tan(派+x)cot(派-x)
化简:sin(2派-x)tan(派+x)cot(-x-派)/tan(3派-x)cos(派-x)
已知(x)=[sin(π-x)cos(2π-x)tan(-x+π)]/[cos(-π/2+x)]
证明tan^2x-sin^2x=tan^2 sin^2x