若cos(π/4-x)=-4/5 5π/4＜x＜7π/4 求 sin2x-2sin²x/1+tanx 的值写出带入的公式 很详细的加20

cos(2x-π)/[根号2cos(x+π/4)]=-1/5,0 若cos(x+y)=4/5,cos(x-y)=-4/5,且3π/2 三角函数解方程 (cos 3x)^3+ (cos 5x)^3 = 8 (cos 4x)^3 (cos x)^3 化简sin(3π-x)cos(x-3/2)cos(4π-x)/tan(x-5π)cos(π/2+x)sin(x-5/2π) 化简sin(3π-x)cos(x-3/2)cos(4π-x)/tan(x-5π)cos(π/2+x)sin(x-5/2π) cos(π/4+x)=3/5,17π/12 cos(π/4+X)=3/5,17π/12 cos(π/4+x)=3/5,17π/12 cos(π/4+x)=3/5,17π/12 cos(π/4+x)=3/5,17/12π cos(π/4+x)=3/5,17π/12 cos(π/4+x)=3/5,17π/12 cos(π/4+x)=3/5,-17π/12 cos(π/4+x)=5/13.且0 已知cos(π/4+x)=3/5 ,0 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 若cos（x+y)=4/5,cos(x-y)=-4/5,且90 若cosx=2/3,x是第四象限角,求sin(x-2π)+sin(-x-3π)cos(x-3π)/cos(π-x)-cos(-π-x)cos(x-4π)的值