JEE Main 2019 (Online) 11th January Evening ShiftQuestion 1
A circle cuts a chord of length $4a$ on the $x$-axis and passes through a point on the $y$-axis, distant $2b$ from the origin. Then the locus of the centre of this circle, is :
Parabola
Solution
Centre $(h,k)$: $r^2=k^2+4a^2$ and $h^2+(k-2b)^2=r^2$, giving $h^2-4bk+4b^2-4a^2=0$, a parabola.