Exterior Angles of Polygons

[b]Click the "▶" button. Observe the angles turned by the car at the corners.[br]Drag the green points. Check the "Show Measurement" box to see the measurements of the angles.[/b]
[b]1. What is a + b + c + d + e, the total angles turned by the car?[br]2. a, b, c, d, e are called the exterior angles of the convex pentagon ABCDE.[br]  In general, what is the sum of all exterior angles of a convex polygon?[br]3. How would you modify the result if the pentagon ABCDE is NOT convex?[br][/b][br]Anthony Or. GeoGebra Institute of Hong Kong.