Final answer:
The radius of the circle with the equation (x+12)²+(y+3)²=225 is 15 units.
Step-by-step explanation:
To determine the radius of the circle with the equation (x+12)²+(y+3)²=225, we recognize that this is the standard form of a circle's equation, which is (x-h)²+(y-k)²=r², where (h, k) is the center of the circle and r is the radius. In our case, h = -12 and k = -3, but these values do not affect the radius. The radius is the square root of the number on the right side of the equation, which is 225. Therefore, the radius r is the square root of 225, which is 15 units.