Question

Find the focus and directrix of the parabola with the equation x² = -22y.

Answer 1

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Answer:

  focus: (0, -5.5)

  directrix: y = 5.5

Step-by-step explanation:

The equation compares to the form ...

  x² = 4py

where 4p = -22   ⇒   p = -22/4 = -5.5.

The value of p is the distance from the vertex to the focus. The negative value means the focus is below the vertex at (0, -5.5).

The directrix is above the vertex by the same amount, so is y = 5.5.