Answer:
The length of the rectangular pen is 40ft. The width of the rectangular pen is 20ft
The diameter is a line that stretches across the middle of a circle from end to end. The radius is one half of this line, stretching from the center of the circle to a point on the side of the circle. This means that the diameter is 2 times the length of the radius. 2 times 2 is 4, meaning that the diameter is 4 inches.
Feet are bigger.
Inches are smaller.
You need more inches to make the same distance.
Just like:
Gallons are bigger.
Ounces are smaller.
You need more ounces to make the same volume.