Dale Copy of Sum of Exterior Angle of Polygon
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?
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?
Do the same for pentagon, hexagon, and pentadecagon. Are there any similarities?
Note 2 things about exterior angles of polygons:
1) their sum is always 360 degrees; and
2) each exterior angle is supplementary to it's adjacent interior angle.
1) To find the number of degrees for each exterior angle of a regular polygon, divide 360 degrees by the number of angles. Answer below.
2) To find x, write the equation setting up the 5 exterior angles to add up to 360 degrees. Answer below.
3) Be careful with this one. First find the value of x by setting up an equation where the 3 exterior angles add up to 360 degrees. Use that value of x and substitute it back in to find each exterior angle. Now you can find angle BCA (interior angle) by r
Answer section.
1. 2. 3.