How to Calculate the Radius of a Circle Without the Diameter

Learn to find the radius of a circle using circumference or area formulas without knowing the diameter.

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To find the radius of a circle without knowing the diameter, use the formula radius (r) = circumference (C) / (2π) if you have the circumference. Alternatively, if you have the area (A), use radius (r) = √(A/π). These formulas help you determine the radius quickly and effectively.

FAQs & Answers

  1. What is the formula for the radius using circumference? The formula for finding the radius from circumference is radius (r) = circumference (C) / (2π).
  2. How do you find the radius if you have the area? If you have the area (A), the radius can be calculated using the formula radius (r) = √(A/π).
  3. Can you find the radius without using pie? No, π (pi) is essential in calculations involving circles since it defines the ratio of a circle's circumference to its diameter.
  4. Why is finding the radius important in geometry? Finding the radius is crucial for understanding circle properties, calculating areas, and solving various real-world problems.