How to figure distance around a circle

A secondary school revision resource for GCSE Maths about higher level shapes and circles. For any circle , the circumference is: 3. However, the diameter is equal to × radius, (2r), so we can also write this formula as: C = 2πr. It could be called the perimeter of the circle.

Unlike triangles, rectangles, and other such figures, the distance around the outside of the circle is called the circumference rather than the perimeter-the concept, however, is essentially the same.

Pi is the ratio of the circumference to the .

Try this Drag the orange dots to move and resize the circle.

The circumference is shown in blue. Note the radius changes and the circumference is calculated for that . These units are related as follows: mm = cm. Circumference is often misspelled as circumfrence. Calculate the area, circumference and radius of circles. Free online calculator for circles and other geometry problems.

The perimeter is the length around . The radius is half of the diameter. All of these values are related through the . However, circles are measured differently than these other shapes —you even. Check out this tutorial to learn about. To do either of these calculations , you will need to use the number π. A linear measurement refers to any one-dimensional measurement of distance, such as feet, inches or miles.

But what is the formula to find the circumference? The distance around the edge of the circle is called the circumference. In the figure above, drag the orange dots around and see that the diameter never changes. R represents the radius, the distance from the center of the circle to the outside.

The Pythagorean theorem then says that the distance between the two points is the square root of the sum of the squares of the horizontal and vertical sides: distance . Here are the vocabulary words in this Concept. Radius the measure of the distance half-way across the circle.