?
What is the directrix of a parabola whose equation is (y +
3)² = 8(x-3)?
O x = 5
Oy = -5
Ox=1
Oy = -1
Done
Answers
The directrix of the parabola with equation (y + 3)² = 8 · (x – 3) is equal to y = – 5. (Correct choice: B)
What is the directrix of a parabola?
According to the given statement, we have a parabola of the form (y – k)² = 4 · p · (x – h), whose axis of symmetry is parallel to the x-axis. The directrix is always perpendicular to the axis of symmetry and therefore the equation of the directrix is equivalent to x = h – p, where p is the distance from the vertex to the focus.
If we know that the equation of the parabola (y + 3)² = 8 · (x – 3), the equation of the directrix is:
y = – 3 – 2
y = – 5
The directrix of the parabola with equation (y + 3)² = 8 · (x – 3) is equal to y = – 5. (Correct choice: B)
What is the directrix of a parabola?