Why is the area of a circle proportional to the square of its radius? And why is that ratio the same as the ratio of the circumference to the diameter?

How do you find the area of a circle? Can you measure the area of a circle and use that to find a value for Pi?

Learn about the definition of pi in relation to a circle with this BBC Bitesize Maths article. For students between the ages of 11 and 14.

I am Pi, the ratio of the circumference of a circle to its diameter. Picking up the phone here at the Smithsonian, I set out to find out more about Pi and how it is represented in the national ...

What Is a Circle? My favorite way to define a circle is in terms of how to draw one. In the episode What Is Pi? we learned how to draw a circle arts-and-crafts style. To do this, start by cutting ...

How to Solve for Radius in Excel. The radius of a circle or a sphere is the distance between the center and the edge. The radius can be used to calculate a circle's diameter, area and circumference.

Letter Published: 02 April 1914 A Triangle that gives the Area and Circumference of any Circle, and the Diameter of a Circle equal in Area to any given Square G. B. MATHEWS Nature 93, 110 (1914 ...

The mathematical constant, which is the ratio of a circle’s circumference to its diameter, can be used to find the area or circumference of a circle -- or of that pie you’re hopefully enjoying ...