# Geo5.1.45

From Example Problems

The line meets the parabola at P,Q. The lines joining P and Q to the focus meet the parabola in M,N.Show that the equation to MN is

Let be the given points.

Therefore equation to PQ is

Given equation of PQ is . Let this be 2.

Given PM,QN are the focal chords.If M and N are the points t3 and t4, then

Equation to MN is

Substituting from 2,

Therefore,