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.

In 1880, the German mathematician Ferdinand von Lindermann proved that pi is a transcendental number and that squaring a circle is impossible under the constraints of Euclidean geometry.

Remember that the third side — which is equal to 3√2 — is the circle's diameter. We're trying to find circumference, which, as stated earlier, is equal to pi times diameter (c = πd).

As we celebrate again in 2018, here are some Pi Day facts you should know. What Is Pi? Pi represents the ratio of a circle’s circumference to its diameter.

Known around the world as "Pi Day," it’s a time to celebrate one of mathematics' most famous constants: Pi, the ratio of a circle's circumference to its diameter, approximately 3.1415.

Archimedes estimated Pi by drawing two 96-sided polygons inside and outside of a circle. He could then determine an upper and lower bounds for the value of Pi.