Find the circumference of a circle with a radius of 5 mm . A. \( 30 \pi \mathrm{~mm} \) (B) \( 5 \pi \mathrm{~mm} \) (C) \( 25 \pi \mathrm{~mm} \) (D) \( 10 \pi \mathrm{~mm} \)

To find the circumference of a circle, you can use the formula \( C = 2\pi r \), where \( r \) is the radius. In this case, the radius is 5 mm. Plugging the value in, we have: \[ C = 2\pi(5) = 10\pi \mathrm{~mm} \] So, the correct answer is (D) \( 10 \pi \mathrm{~mm} \). For a bit of fun, did you know that the concept of pi (π) has been around for thousands of years? Ancient civilizations like the Egyptians and Babylonians had their own approximations for pi! They used it not just in mathematics, but also in their engineering projects, proving that geometry was crucial long before calculators came along! In real-world applications, understanding the circumference is vital when dealing with circular objects, like designing wheels or even making pizzas! For example, a pizzeria chef might want to know the circumference of pizza dough to ensure it stretches out perfectly for that delicious, golden crust. Now that’s a tasty application of geometry!