How do you find the circumference of a circle?

To find the circumference of a circle, one can use either of the two formulas provided: C = πd or C = 2πr.

The formula C = πd utilizes the diameter of the circle (d), which is the distance across the circle through its center. The formula C = 2πr uses the radius (r), which is the distance from the center of the circle to any point on its circumference. Since the diameter is twice the radius (d = 2r), both formulas are equivalent and can be used interchangeably depending on the information available.

Understanding the relationship between circumference, diameter, and radius is fundamental in geometry, as it helps in calculating the perimeter of circles in various applications, from real-world problems involving circular dimensions to theoretical computations within the field.

The other formulas presented in the choices do not accurately represent the circumference of a circle. For instance, C = πr represents an incorrect relationship, as it should include the multiplication by 2 to account for the complete path around the circle. C = 4r inaccurately suggests that the circumference is four times the radius, which does not hold true as the relationship between radius and circumference is governed by a factor of π. Lastly, C =