Final answer:
The dog has about 1257 square feet of running area.
Step-by-step explanation:
To find the running area of the dog, we need to find the area of the circle with a radius of 20 ft.
The formula to find the area of a circle is A = πr^2, where A is the area and r is the radius.
Using this formula, we can calculate the area as follows:
A = π(20^2) = 400π ft²
Rounding to the nearest square foot, the dog has about 1257 ft² of running area.