Question

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

Answer 1

Answer:

-The answer for the radius:

$\sqrt{61} = r$

Step-by-step 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:

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

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

$25+36=r^2$

$61 = r^2$

$\sqrt{61} = \sqrt{r^2}$

$\sqrt{61} =r$

So, therefore the radius is $\sqrt{61}$ .