Page 4 - LESSON NOTES
P. 4
Note: The standard equations of parabolas have focus on one of the coordinate axis; vertex at
the origin and thereby the directrix is parallel to the other coordinate axis.
Latus rectum: Latus rectum of a parabola is a line segment perpendicular to the axis of the
parabola, through the focus and whose end points lie on the parabola
To find the Length of the latus rectum of the parabola y2 = 4ax. By the definition of the
parabola, AF = AC. But AC = FM = 2a.Hence AF = 2a and since the parabola is symmetric with
respect to x-axis AF = FB and so AB = Length of the latus rectum = 4a
Four Common Forms of a Parabola:
