The acute angle between the pair of lines cosα+sinαx2−2xycosα+cosα−sinαy2=0 is

If θ is acute angle between pair of lines represented by the equation ax2+2hxy+by2=0 then cosθ=a+b(a−b)2+(2h)2For the equation cosα+sinαx2−2xycosα+cosα−sinαy2=0, the values are a=cosα+sinα,2h=−2cosα,b=cosα−sinαHence, cosθ=2cosα4sin2α+4cos2α=2cosα2=cosαTherefore, θ=α