Question

Define double ordinate.

Answer 1

Double ordinate can be described as any chord of the parabola that is perpendicular to the axis and passing through any point on the parabola is called double ordinate.

Consider a chord passing through any point $P$ on the parabola and is perpendicular to the axis is called double ordinate. The latus rectum is an illustration of double ordinate that passes through the focus of the parabola.