Pythagoras discovered the Pythagorean Theorem. The Pythagorean Theorem is the basis of trigonometry. GPS satellites use Pythagoras' ideas to find where people are on Earth with a system called triangulation.
Although the mathematical facts of the theorem existed - even before humans did - the theorem itself did not exist until Pythagoras thought of it. In that sense, he did not FIND it because it did not exist until he had thought of it.