The equation shown in the image is:

$C = 2 \pi r$

This is the formula for the circumference $C$ of a circle, where:

• $r$ represents the radius of the circle, and
• $\pi$ is the mathematical constant approximately equal to 3.14159.

Would you like to go over an example using this formula, or do you have any specific questions about it?

Here are 5 related questions to consider:

1. How do you find the radius if the circumference is given?
2. How does the diameter relate to the circumference formula?
3. What happens to the circumference if the radius doubles?
4. How is this formula used in real-life applications (e.g., engineering, architecture)?
5. What is the significance of $\pi$ in the formula, and why does it appear?

Tip: To convert between diameter and radius, remember that the diameter is twice the radius: $d = 2r$.