Answer: The radius of the given circle is 4 units.
Step-by-step explanation: We are given to find the radius of the circle with the following equation :

We know that
the standard equation of a circle with center at the point (h, k) and radius r units is given by

From equation (i), we have

Comparing it with the standard equation, the radius of the circle is given by

Thus, the radius of the given circle is 4 units.