What is the formula to calculate the circumference of a circle?

The circumference of a circle is defined as the distance around the circle. The formula to calculate it is based on two key measurements: the diameter and the mathematical constant π (pi).

When you use the formula that involves π multiplied by the diameter, you are effectively measuring the full extent of the circle's boundary. The diameter of a circle is the distance across the circle through its center, and π is a constant approximately equal to 3.14159. Therefore, the formula ( C = \pi \times d ) accurately captures the relationship between the diameter and the circumference.

While the radius, which is half the diameter, can also be used in calculating circumference, the direct relationship between circumference and diameter through π is the most straightforward and widely used formula. Other options do not represent the correct relationship for calculating circumference, specifically the multiplication of diameter and height or the radius alone without π.