A circle touches the line $L$ and the circle $C_{1}$ externally such that both the circles are on th

Question

A circle touches the line $L$ and the circle $C_{1}$ externally such that both the circles are on the same side of the line, then the locus of centre of the circle is\

Professor PC Thomas Classes · Answer

(c) : Let $C$ be the centre of the required circle.\ Now draw a line parallel to $L$ at a distance of $r_{1}$ (radius of $C_{1}$ ) from it.\ Now $C P_{1}=A C \Rightarrow C$ lies on a parabola.\