Move the slider to change the number of sides on the polygon - can you use this information to help you find a rule to work out the sum of interior angles in a polygon?
What is the sum of interior angles for a triangle? Can you see a relationship between the number of sides of a polygon and the amount of triangles that "fit" inside it? How can this help you to work out the sum of interior angles for another polygon? Can you find a rule to work out the sum of interior angles in any polygon?