Locus 8 (equidistant from a fixed point and a straight line)

A moving point P is equidistant from a fixed point A and the horizontal straight line L. Move the point P to find out the locus of P.
Describe the locus of P.
Luk
– WMY_hk

Information: Locus 8 (equidistant from a fixed point and a straight line)