To find how much fencing is need we first need to find the circumference of the tree.

To do this we first need to find the diameter of the tree.

The diameter is twice the radius: d = 2r

Since we know the radius, we can double that to get the diameter

d = 18.75 ft (2)

d = 37.5 ft

Circumference: pi * diameter

c = 3.14d

c = 3.14(37.5 ft)

c = 117.75 ft

Therefore you would need 117.75 ft of fencing to border the tree; however, because we are look at an eight foot border from the tree, that adds 8 feet to the radius, 18.75 ft and creates a new radius of 26.75 ft. So we do the same thing as before but with the new radius.

To do this we first need to find the diameter of the tree.

The diameter is twice the radius: d = 2r

Since we know the radius, we can double that to get the diameter

d = 26.75 ft (2)

d = 53.5 ft

Circumference: pi * diameter

c = 3.14d

c = 3.14(53.5 ft)

c = 167.99 ft

This makes the total amount of fencing need for an 8 foot border: 168 feet of fencing.