# What is the equation of the parabola with a focus at (3,18) and a directrix of y= -21?

##### 1 Answer

Jul 29, 2017

#### Explanation:

Parabola is the locus of a pint, which moves so that its distance from a point called focus and a line called directrix is always equal.

Let the point on parabola be

its distance from focus

and distance from directrix

Hence equation of parabola is,

or

or

graph{(x^2-6x-78y-108)((x-3)^2+(y-18)^2-2)(x-3)(y+21)=0 [-157.3, 162.7, -49.3, 110.7]}