The image shows the equation for the circumference of a circle:

$C = 2\pi r$

Where:

• $C$ is the circumference of the circle.
• $r$ is the radius of the circle.
• $\pi$ (pi) is a mathematical constant approximately equal to 3.14159.

This formula is used to calculate the distance around a circle (its circumference) given its radius $r$.

Would you like to explore details on how this formula is derived or see specific examples of using it?

Here are 5 questions that might deepen your understanding:

1. How do you calculate the circumference if you know the diameter of the circle instead of the radius?
2. What is the relationship between the radius and the diameter of a circle?
3. How would the formula change if you wanted to calculate the area of the circle?
4. How can you use this formula to find the radius if the circumference is known?
5. How does this formula apply in real-world problems, such as determining the length of a track?

Tip: If you know the diameter of a circle, you can use the formula $C = \pi d$, since $d = 2r$.