Define double ordinate
We will use the concept of the parabola to answer this question.
Answer: Double ordinate can be defined as any chord of the parabola which is perpendicular to the axis and passing through any point on the parabola is called double ordinate.
Let's see what double ordinate is.
Let 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 example of double ordinate that passes through the focus of the parabola.
Let's take an example for a parabola, y2 = 4ax.
The double ordinate can be shown as in the figure below.
Here, the line segment AB is the double ordinate of the parabola.