Question

Write the equation in standard form for the circle with center (9,
-
4) and radius 9.

Answer 1

`(x-9)^(2)+(y+4)^(2)=81`

Explanation:

we know that

The equation of a circle in standard form is equal to

`(x-h)^(2)+(y-k)^(2)=r^(2)`

where

(h,k) is the center

r is the radius

In this problem we have

`(h,k)=(9,-4)`

`r=9\ units`

substitute

`(x-9)^(2)+(y+4)^(2)=9^(2)`

`(x-9)^(2)+(y+4)^(2)=81` ----> equation of the circle in standard form