Side-based
Right triangles whose sides are of integer lengths, Pythagorean triples, possess angles that are never rational numbers of degrees. They are most useful in that they may be easily remembered and any multiple of the sides produces the same relationship. Using Euclid's formula for generating Pythagorean triples, the sides must be in the ratio
where m and n are any positive integers such that m>n.
Read more about this topic: Special Right Triangles