1/cos(x) - tan(x) = 3 求sin(x)1/cos(x) - tan(x) = 3求sin(x)

为什么cos(sin(tan x)))=1 求证：tan x/2=sin x/(1+cos x) 求证：1-sin(x)=cos(x)*tan(x/2) 1/cos(x) - tan(x) = 3 求sin(x)1/cos(x) - tan(x) = 3求sin(x) (sin x) + (cos x) = (tan x) + 1/(tan x)0 为什么1/cos^2x=tan^2x? 证明：(1 + tan x) / (sin x + cos x) = 1 / cos x 1-tan*2x/1+tan*2x=cos*2x-sinx求证 (tan x+1/tan)cos^2 x等于? 证明 (tan xsin x)/(tan x-sin x)-(1+cos x)/sin x上面打错了 (tan xsin x)/(tan x-sin x)=(1+cos x)/sin x 求证：1-2sinxcosx/cos方x-sin方x=1-tan/+tan 求证(3-sin^4 x-cos^4 x)/2cos^2 x=1+tan^2 x+sin^2 x 证明(1-2sin x cos x )/(cos^2x-sin^2x)=(1-tan x)/(1+tan x)谢谢谢谢 急 (2sin^2x-sinxcosx+cos^2x)/sin^2x+cos^2x=(2tan^x-tanx+1)/(tan^2x+1)怎么算 (2sin^2x-sinxcosx+cos^2x)/sin^2x+cos^2x=(2tan^x-tanx+1)/(tan^2x+1)怎么算 (2sin^2x-sinxcosx+cos^2x)/sin^2x+cos^2x=(2tan^x-tanx+1)/(tan^2x+1)怎么算 求证 （1—tan^2X)/(1+tan^2X)=cos^2X—sin^2X （2-cos^2x)(2+tan^2x)=(1+2tan^2x)(2-sin^2x)