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.

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.

…and you can see that the ribbon is just over 3 times the diameter of 1 circle. This number, called π (or pi), is approximately 3.14. You have shown that the circumference of a circle is π × ...

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.

Determined to fulfil the request, he set out to calculate the circumference and area of a circle using only a straight edge and compass.