Question

What is the exact circumference of the circle?

Answer 1

Data:

Formula: diameter = 2*radius

Formula: (Circle length)
$C = 2* \pi *r$

Solving: Using the data
diameter = 2*radius
20 = 2*r
2r = 20
$r = \frac{20}{2}$
$\boxed{r = 10\:ft}$

Now, replace in the circumference length formula
$C = 2 \pi *r$
$C = 2 \pi *10$
$\boxed{\boxed{C = 20 \pi \:ft}}\end{array}}\qquad\quad\checkmark$

Answer:
The exact circumference of the circle is $20 \pi \:ft$