已知4sin^2x-cos^2x+3cosx=0求(cos2x-cos^2x)/(1-cot^2x)

已知sin(x)+3cos(x)=2,求sin(x)-cos(x)/sin(x)+cos(x)=? 已知cos 2x=3/5,求sin^4 x+cos^4 x的值 已知sin2x=(sinθ+cosθ)/2,cos^2x=sinθcosθ,那么cos2x的值是?2sin2x=sinθ+cosθ,平方得：4(sin2x)²=1+2 sinθcosθ,将cos²x=sinθcosθ代入得:4(sin2x)²=1+2cos²x,4(1- cos²2x) =1+2cos²x,4(1- cos²2x) =1+(1+co 已知tan=2,求(cos x+sin x)/(cos x-sin x)+sin^2x 已知sin[a-b]cos a-cos[b-a]sin a=3/5,b是第三象限角,求sin[b+5π/4]的值第一题1/2cos x-√3/2sin x第二题√3sin x+cos x第三题√2[sin x-cos x]第四题√2cos x-√6sin x 证明sin^2(x)+cos^2(x+30)+sin(x)cos(x+30)=3/4 已知:tan x=2 求:sin x+cos x/sin x-cos x=? 化简[1-(sin^4x-sin^2cos^2x+cos^4x)/(sin^2)]+3sin^2x 已知f(x)=cos^4x-2根号3sinxcosx-sin^4x 化简 已知tgx= -2,求(sin*2x+3cos*2x)/(3sin*2x-cos*2x) 已知tgx=-2,求(sin²x+3cos²x)/(3sin²x-cos²x) 2(sin^6x+cos^6)-3(sin^4x+cos^4x) 已知tanx=-3/4,求2sin^2 x+3sin xcos x-cos^2 x 已知sin(x+π/3)=1/4,求sin(2π/3-x)+cos²(π/6-x) (1-(sin^4x-sin^2xcos^2x+cos^4x)/sin^2x +3sin^2x 化简[1-(sin^4 x-sin^2 xcos^2 x+cos^4 x)]/(sin^2 x)+3sin^2 x 化简sin^4x-sin^2x+cos^2x 化简:sin^4 x-sin^2 x+cos^2 x