We all know that a triangle is made up of three sides. But do the lengths of those sides matter? Or can any three side lengths make up a triangle?

You might remember your Geometry teacher talking about the *Triangle Inequality Theorem*. It tells us that some triangles just aren’t possible. Imagine if I gave you three sticks with lengths of 10 inches, 2 inches and 5 inches and I told you to make a triangle. Try as hard as you’d like; you won’t be able to do it. You’ll end up instead with something that looks like this: