When the focus and directrix are used to derive the equation of a parabola, two distances were set equal to each other.

Question

Revolt · Accepted Answer

The distance between the directrix and is set equal to the distance between the and the same point on the parabola.:

a point on the parabola

The distance between the directrix and is set equal to the distance between the and the same point on the parabola.:

focus

Parabolas