Question

A circle is centered on point (-2,-1). The circle passes through the point (-7,-7). What is its radius?

Answer 1

-The answer for the radius:

`√(61) = r`

Explanation:

-The equation of a circle is:

`(x-h)^2+(y-k)^2=r^2` (where the center is known as
`(h,k)`, the point is
`(x,y)` and the radius known as
`r`).

-Use both the center (-2,-1) and the point (-7,-7) for the equation:

`(-7+2)^2+(-7+1)^2=r^2`

-Then, solve the equation to get the radius:

`(-7+2)^2+(-7+1)^2=r^2`

`(-5)^2+(-6)^2=r^2`

`25+36=r^2`

`61 = r^2`

`√(61) = √(r^2)`

`√(61) =r`

So, therefore the radius is
`√(61)` .