Question

what is the equation of the directrix of the parabola shown in the figure below?

Explanation:

Step1: Identify the directrix from the graph

The directrix is the horizontal dashed - line.

Step2: Determine the equation of the horizontal line

The horizontal line passes through $y = 10$. The equation of a horizontal line is of the form $y = k$, where $k$ is the $y$ - coordinate of all points on the line.

Answer:

$y = 10$