There are a select few tidbits that adults remember from high school, such as what the animals in Animal Farm really represented or what assassination prompted WWI. The Pythagorean theorem (or Pythagoras’ theorem) might be the only thing anyone remembers from high school math—and not even by name either. Well, because the internet is the best professor any of us have ever had, here’s a GIF that explains exactly how two sides of a right triangle can help us find the length of the the third.