9/15/12 — Happy Right Triangle Day!

Happy Right Triangle Day!  Today, on 9/15/12, we celebrate a favorite triangle:  the 9-12-15 right triangle.

We know this triangle is right because the side lengths satisfy the Pythagorean Theorem.

$9^2 + 12^2 = 15^2$

This isn’t the only Right Triangle Day this year.  And these two right triangles work together to form one of my all-time favorite triangles!