Question

Determine the equation of the circle with radius 99 and center (-1,-8)(−1,−8).

Answer 1

Equations of Circles

Generally, you'd see the equation of a circle organized in the following format:

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

• 
  `(h,k)` is the center
• 
  `r` is the radius

To determine the equation given the center and the radius:

1. Plug both pieces of information into the general equation
2. Simplify

Solving the Question

We're given:

• Radius: 99
• Center: (-1,-8)

Plug the radius and center into the equation as r and (h,k):

`(x-(-1))^2+(y-(-8))^2=99^2\\(x+1)^2+(y+8)^2=9801`

Answer

`(x+1)^2+(y+8)^2=9801`