A simple guide on how to show the angles in triangle add up to 180 degrees, aimed at students aged 11 to 14.

Everyone learns the number one rule about triangles in high school: the angles of a triangle add up to 180 degrees. But did you know that sometimes they don't? Triangles are much more interesting ...

If you draw straight lines connecting those cities to make a triangle on the surface of the globe, you will find that the interior angles of that triangle add up to more than 180 degrees.