Equation problem: the equation sin2x · sin4x-sinx · sin3x = a of X has a unique solution in X ∈ [0, Π]. Find the value of real number a

Equation problem: the equation sin2x · sin4x-sinx · sin3x = a of X has a unique solution in X ∈ [0, Π]. Find the value of real number a

a=sin2x*sin4x-sinx*sin3x=sin2x*(2sin2x*cos2x)-(cos2x-cos4x)/2=2(1-cos^2 2x)cos2x-(cos2x-(2cos^2 2x-1))/2=-2cos^3 2x+cos^2 2x+3cos2x/2-1/2=(cos2x-1)(-2cos^2 2x-cos2x+1/2)=-4(cos^2 x-1)(2cos^2 x-(3+√5)...