This topic is in the 'Real Numbers and Right Triangles' section. At first, you might think that it's weird to combine real numbers and right triangles together in one section. What does one have to do with the other? Well, it's actually quite an amazing story, and it has to do with the Pythagorean Theorem. Let's step back and start with a 1 by 1 square, and cut along the diagonal, you'll get a right triangle with legs having a length of 1. Now what if you needed to find the length of the diagonal? Well, the Pythagorean Theorem comes into play here, and tells us that when you square the length of the diagonal, you get 2 square inches. That leads us to a deep question, which is what is the square root of 2 equal to? We can find an approximate number that comes close, but it turns out that there is no way to express the square root of 2 using rational numbers. In other words, we have to invent a new type of number to handle something as seemingly simple as the length of the diagonal of a 1 by 1 square! Those numbers are called irrational numbers, and the combination of rational and irrational numbers gives us the real numbers. That's why real numbers and right triangles are connected, and the tutorials in this section will show you a lot of cool properties and interesting problems related to these topics!