Slide 1: Angle Sum Property Of Polygons. Slide 2: What Exactly is a Polygon?. Slide 3: Starting Simple: The Triangle!. Slide 4: The Trick: Dividing into Triangles!. Slide 5: Discovering the Pattern: Quadrilaterals. Slide 6: The Grand Formula Revealed!. Slide 7: Putting the Formula to Work!. Slide 8: Beyond the Basics: Regular Polygons & Exterior Angles