The directrix of the conic described by is
A) To the right of the pole
B) To the left of the pole
C) Above the pole
D) Below the pole

Question

The directrix of the conic described by  is
A) To the right of the pole 
B) To the left of the pole 
C) Above the pole 
D) Below the pole

Quizplus · Accepted Answer

In a parabola, the directrix is always perpendicular to the axis of symmetry and is located on the opposite side of the vertex from the focus. Since the vertex of the given conic is at the origin and the focus is (2,0), the axis of symmetry is the x-axis. Therefore, the directrix must be a vertical line, and since the focus is to the right of the origin, the directrix must be to the left of the pole. Therefore, the correct answer is B) To the left of the pole.

The Directrix of the Conic Described by Is