Hello!
The answer is: The length of the ratio is 18 feet.
Why?
There are two ways to calculate the circumference of a circle:
![C=\pi d\\C=2\pi r](https://img.qammunity.org/2020/formulas/mathematics/high-school/ca59hs9ttpou31qq57gzy1d6ovm87a3w43.png)
Since we are looking for the length of the radius, let's work with the second formula.
From the statement we know that the circumference of the cirble is 36π, so we need to isolate the ratio:
![C=2\pi r\\\\36\pi feet=2\pi r\\\\r=(36\pi feet)/(2\pi )=18feet](https://img.qammunity.org/2020/formulas/mathematics/high-school/sp2audon5ceb4hdwdv9kctr6pwby9vuhfb.png)
So, the length of the ratio is 18 feet.
Have a nice day!