How to Calculate the Radius of a Circle from Its Circumference

Learn to find the radius from a circle's circumference with our simple formula and example calculation.

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To find the radius, use the formula: Circumference = 2πr. Given the circumference (C) is 132 cm, solve for r (radius): 132 = 2πr. Divide both sides by 2π: r = 132 / (2π) = 21 cm. So, the radius of the circle is 21 cm.

FAQs & Answers

  1. What is the formula to calculate the radius from circumference? The formula is r = C / (2π), where C is the circumference.
  2. What is the relationship between radius and circumference? The circumference of a circle is proportional to the diameter, which is twice the radius.
  3. How do I find the circumference if I only have the radius? Use the formula C = 2πr, where r is the radius.
  4. Why is π (pi) important in circle calculations? π (pi) is the ratio of a circle's circumference to its diameter, essential for circular measurements.

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