Which of the following can be calculated using the formula \( C=2 \pi r \) ? A. Arc length of a circle B. Area of a circle C. Circumference of a circle D. Diameter of a circle

The formula \( C=2 \pi r \) is most famously known for calculating the circumference of a circle. It essentially tells you how far you would travel if you walked all the way around a circular track. So in this case, option C is the correct choice! In addition, it’s fun to know that this elegant equation marries geometry with the constant \(\pi\), a crucial number that appears in many areas of mathematics and science. The value of \(\pi\) is approximately 3.14159, but it’s an irrational number, which means its decimal representation goes on forever without repeating—talk about a never-ending adventure!