The number pi is defined as the ratio of the circumference of any circle
to its diameter. Its value is approximately 3.14. That it is
irrational means that it cannot be expressed as the ratio of two integers
and that in turn means that it cannot be expressed as a finite or repeating
decimal; its expansion must be infinitely long with no repeating pattern.
To prove that pi is irrational.... read on!
We do it by assuming the contrary, ie that pi is rational, and then show that this leads to a contradiction
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