# Relationship between radius and diameter

### Relation Between the Circumference and Diameter | eMathZone

If you know the diameter. Given the diameter of a circle, the radius is simply half the diameter: radius. = D. 2. where: D is the diameter of the circle. The relation of the radius to the diameter gives us one of the formulas involving the diameter. Let's see what that is. The diameter of a circle is the greatest width of the circle or twice the radius of a circle, which is the midpoint of the circle to the edge. By knowing either the.

Watch a modern-day mathematician recreate the Eratosthenes method and show how to calculate Circumference TLF-IDM This sequence of three lessons explores the properties of circles, in particular the relationship between the diameter and circumference.

In the first lesson, students use a cylinder containing three tennis balls to understand that a circumference is 'three and a bit' times the diameter. They then complete five different See how to use a third of the base area to work out the volume of a pyramid or a cone.

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Can you guess what other dimension is needed? See how to use a formula that includes the measurement of the diameter and pi.

TLF-IDM This is an online resource that introduces the concept of pi as the ratio of a circle's circumference to its diameter. The buttons at the bottom of the screen provide links to an animated demonstration of how an approximation of pi can be determined by measuring the circumference, the first digits of pi and a mnemonic The approximate value of pi and the rules for finding the circumference and area of a circle are given.

Students attempt questions that give immediate feedback. They can then be introduced to pi, either through a library exploration or with your guidance.

In the Bible 1 Kings 7: Another approximation is 3.