# What is the equation in standard form of the parabola with a focus at (-2,3) and a directrix of y= -9?

##### 1 Answer

#### Explanation:

Sketch the directrix and focus (point

Choose a general point on the parabola (called

Join

A horizontal line from

By the parabola definition, point

Find expressions for the distances

Then use Pythagoras to find AB:

and since

This is your parabola equation.

If you want it in explicit