Question

Writing an equation of a circle given at Center and radius or diameter

Answer 1

The equation of a circle with Center (a, b) and Radius 'r' is given by,

`(x-a)^2+(y-b)^2=r^2`

Given,

Center (-7, -4)

Diameter = 8

We know the radius is half of diameter.

So,

Radius = 8/2 = 4

Now we can write the equation of the cirle,

`\begin{gathered} (x-a)^2+(y-b)^2=r^2 \\ (x-(-7))^2+(y-(-4))^2=4^2 \\ (x+7)^2+(y+4)^2=16 \end{gathered}`

Answer
`(x+7)^2+(y+4)^2=16`