cos2x/根号2cos(x+π/4)=1/5,0
cos2x/根号2cos(x+π/4)=1/5,0
已知tanx=-4/3,试化简(2+cos2x)/[(根号2)·cos(x-π/4)-sin2x]
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sinx/2-2cosx/2=0求cos2x/根号2cos(π/4+x)sinx的值
已知函数f(x)=sinx/2-2cosx/2=0 (1)求tanx的值 (2)求cos2x/根号2cos(π/4+x)
cos[2(π-x)]=-cos2x对不对?
cos^2 x=(cos2x-1)/2
已知函数f(x)=1/2cos2x+根号3sinxcosx-2cos^2x
已知函数f(x)=根号3sinx/2cosx/2-cos2x/2+1/2,x属于[0,π/2]f(x)跟号3/3求cos
已知x属于(-π/2,0),sinx+cosx=-根号2/31,求cos(x+π/4)的值2.求(cos2x)/[tan
已知sinx/2-2cosx/2=0,求tanx的值;求(cos2x)/(根号2cos(π/4+x)*sinx)的值
若cos(π/2+x)=4/5,则cos2x=