1. What is Radius?

The radius of a circle is the distance from its center to any point on its circumference. It is exactly half the length of the diameter, which is the longest distance across the circle passing through the center.

2. How Does the Calculator Work?

The calculator uses the simple formula:

Where:

• \( Radius \) — Distance from center to edge of circle
• \( Diameter \) — Distance across circle through center

Explanation: Since diameter is always twice the length of the radius, dividing any diameter by 2 gives the corresponding radius.

3. Importance of Radius Calculation

Details: Knowing the radius is essential for many circle calculations including area (\( \pi r^2 \)), circumference (\( 2\pi r \)), and volume of spheres. It's fundamental in geometry, engineering, and physics.

4. Using the Calculator

Tips: Enter the diameter measurement in any consistent units (cm, inches, meters, etc.). The calculator will return the radius in the same units. Diameter must be a positive number.

5. Frequently Asked Questions (FAQ)

Q1: Can I use this for semicircles?
A: Yes, the radius of a semicircle is still half its diameter (the straight edge).

Q2: What if I know circumference instead of diameter?
A: First calculate diameter as \( \frac{Circumference}{\pi} \), then divide by 2 for radius.

Q3: Does this work for spheres?
A: Yes, the same relationship holds for the radius and diameter of spheres.

Q4: Why is radius more commonly used than diameter?
A: Many fundamental formulas (like area) are naturally expressed in terms of radius, making it often more convenient.

Q5: How precise should my diameter measurement be?
A: For practical purposes, measure diameter to the same precision you need for radius. More precision gives more accurate results.