Step-by-step explanation:
To find the radius of a circle and then its equation we must follow the following steps:
-The center is -3 and -1 that is h and k
-The radius of the circle is Half the diameter, we can see in the graph that it is at the value of -3 that is 3
Now knowing the radius and the center we can find the canonical equation of the circumference; then (-3, -1); the radius must be positive;
h, k

Now to obtain the standard or general equation we must solve the operations of the canonical equation that we already found; the standard equation is the following:
