The formula for the circumference $C$ of a circle is:

$C = 2\pi r$

where:

• $\pi$ is approximately 3.14,
• $r$ is the radius of the circle.

Given the radius $r = 13$ ft, substitute this into the formula:

$C = 2 \times 3.14 \times 13 = 81.64 \, \text{ft}$

So, the circumference of the circle is approximately 81.64 ft.

Would you like any further details or clarification? Here are some related questions you might find helpful:

1. How is the circumference formula derived?
2. What is the relationship between the diameter and the radius of a circle?
3. How do you calculate the area of a circle?
4. Can the circumference formula be used to find the radius if the circumference is known?
5. What is the significance of $\pi$ in circles?

Tip: Always use the correct value for $\pi$ (3.1416 or 3.14) depending on the level of precision needed.