1/cos(x) - 1/sin(x)=1,则sin2x的值为多少?拜托各位了,很急.

cos x/sin x+sin x/(1+cos x) 化简. (1+cos x-sin x)/(1-sin x-cos x)+(1-cos x-sin x)/(1-sin x+cos x)=? 怎么证明2(1-sin x)(1+cos x)=(1-sin x+cos x)^2 y=(sin(x)-1)/(cos(x)+(cos(x))/(sin(x)+1)的奇偶性 求证（cos^2 x-sin^2 x)(cos^4 x+sin^4 x)+1/4 sin 2x sin 4x=cos 2x 为什么cos(sin(tan x)))=1 已知(1+sin x)/cos x=-1/2,则cos/(sin x-1)=? 化简(sin x+cos x-1)(sin x-cos x+1)/sin 2x 求证：tan x/2=sin x/(1+cos x) 求证：1-sin(x)=cos(x)*tan(x/2) f'(sin x)=1-cos x 求f''(x) 1/cos(x) - tan(x) = 3 求sin(x)1/cos(x) - tan(x) = 3求sin(x) 证明一个sin&cos的等式证明 1+sin^2(x)+sin^4(x)+sin^6(x)=[1-sin^8(x)]/[cos^2(x)] 2cos x (sin x -cos x)+1 1/(sin x+cos x) 的不定积分 cos x/( 1-sin x)化简 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)