A Pythagorean triple is a list of three numbers that works in the Pythagorean theorem — the square of the largest number is equal to the sum of the squares of the two smaller numbers. The multiple of any Pythagorean triple (multiply each of the numbers in the triple by the same number) is also a Pythagorean triple. They seem to reinvent themselves.

Familiarizing yourself with the more frequently used Pythagorean triples is very helpful. If you recognize that you have a triple, then working with applications is much easier.

The table shows some of the most common Pythagorean triples and some of their multiples.

Common Pythagorean Triples
Triple Triple x 2 Triple x 3 Triple x 4
3-4-5 6-8-10 9-12-15 12-16-20
5-12-13 10-24-26 15-36-39 20-48-52
7-24-25 14-48-50 21-72-75 28-96-100
9-40-41 18-80-82 27-120-123 36-160-164
11-60-61 22-120-122 33-180-183 44-240-244

Here's how to check out a triple and its multiple by using the Pythagorean theorem. Try out the triple 9-40-41:

1. Replace a, b, and c with 9, 40, and 41, respectively.

2. Then replace a, b, and c with the 9-40-41 triple multiplied by 3 (which is 27-120-123).