Question

Write the equation of the circle with center (−1, −3) and (−7, −5) a point on the circle.

Answer 1

Explanation:

The standard form of a circle is

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

We have everything we need to fill this in and solve for the radius.

`(-7-(-1))^2+(-5-(-3))^2=r^2` and

`(-7+1)^2+(-5+3)^2=r^2` and

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

`r^2=40`

Now we can write the equation using the center and the radius we just found:

`(x+1)^2+(y+3)^2=40`