Use the applet below. Check the box next to triangle and then slide the Dilate slider. What do you notice about the 3 exterior angles of a triangle?[br]Now check the box next to quadrilateral and then slide the Dilate slider. What do you notice about the 4 exterior angles of a quadrilateral?[br]Do the same for pentagon, hexagon, and pentadecagon. Are there any similarities?
Note 2 things about exterior angles of polygons:[br]1) their sum is always 360 degrees; and[br]2) each exterior angle is supplementary to it's adjacent interior angle.