A circle has a radius of 7. What is its circumference in terms of π?

A circle has a radius of 7. What is its circumference in terms of π?

• A. 14π
• B. 7π
• C. 28π
• D. 14

Answer: (A)

Circles use the circumference formula C = 2πr, which links the distance around the circle to its radius with the constant π. With a radius of 7, the circumference is C = 2 × π × 7 = 14π. So the circumference in terms of π is 14π. You can also use the diameter (which is twice the radius, 14) in C = πd to get C = π × 14 = 14π, which confirms the result. The other numbers would come from a different radius or from dropping π, which isn’t correct for this circle.

Circles use the circumference formula C = 2πr, which links the distance around the circle to its radius with the constant π. With a radius of 7, the circumference is C = 2 × π × 7 = 14π. So the circumference in terms of π is 14π. You can also use the diameter (which is twice the radius, 14) in C = πd to get C = π × 14 = 14π, which confirms the result. The other numbers would come from a different radius or from dropping π, which isn’t correct for this circle.