The length of latus rectum of the ellipse is .
The chord through the focus and perpendicular to the axis of the ellipse is called its latus rectum. Since ellipse has two foci, so it will have two latus recta.
Let and be the ends of the latus rectum as shown in the given diagram. Since latus rectum passes through the focus, so abscissa of and will be . Now putting in the given equation of ellipse, we have
Since , so putting this value in equation (i), we have
Thus, and . The length of latus rectum is