The equation of the locus of foot of perpendiculars drawn from the origin to the line passing through a fixed point (a,b), is
λ(x−a)+(y−b)=0 is the equation of line.
r=−(−aλ−bλ2+1)
Coordinates of point = {−λ(−aλ−bλ2+1),−(−aλ−bλ2+1)}
h=λ(aλ+bλ2+1),k=aλ+bλ2+1,λ=hk
∴h=h(ah+kbh2+k2)⇒x2+y2=ax+by.