已知sin(π/4-x)=5/13,x属于(0,π/4),求(cos2x)/cos[(π/4)+x]
已知sin(π/4-x)=5/13,x属于(0,π/4),求(cos2x)/cos[(π/4)+x]
已知cos(π/4+x)=5/13,0<x<π/4,求sin(π/4-x)/cos2x
已知sin[(π/4)-x)]=5/13,0<x<π/4.求cos2x/(cosπ/4+
已知0<x<π/4,sin(π/4-x)=5/13,求cos2x/cos(π/4+x)的值
已知0<x<π/4,sin(π/4 -x)=5/13,求cos2x除以cos(π/4 +x)的值
已知0<x<π/4,sin(π/4-x)=5/13,求(cos2x)/(cos(π/4+x))的值.
已知sin(x/2)-2cos(x/2)=0,求tanx的值,求cos2x除以根号2*cos(π/4+x)*sinx的值
已知sin(π-α)=4/5 ,α属于(0.2).求函数f(x)=5/6 cosαsin2x-½cos2x
已知sin x/2 -- 2cos x/2=0.(1)求tan x的值.(2)求 cos2x/(√2cos(π/4+x)
已知函数f(x)=cos2x/[sin(π/4-x)]
已知函数f(x)=cos2x\ sin(x+π\4),求函数f(x)的定义域
1.y=cos^4x+sin^4x 求周期 2.y=(sin2x+sin(2x+π/3))/( cos2x+cos(2x