Answer:
Equation of circle:

Explanation:
Given:
Center of the circle = (-3, -1)
Point on the circle = (1, -1)
In order to find the radius of the circle, we can use the distance formula.
distance =

where:
- x1 and y1 are the coordinates of the center of the circle
- x2 and y2 are the coordinates of the point on the circle
In this case, the distance formula becomes:
radius =

Therefore, the radius of the circle is 4 units.
Now that we know the radius of the circle, we can find the equation of the circle using the following formula:

where:
- h and k are the coordinates of the center of the circle
- r is the radius of the circle
In this case, the equation of the circle becomes:
=

=

This is the equation of the circle.