2. A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others. Polygon

3. Q: Is this a polygon? Why or why not? A: No… Polygons are closed figures.

4. Q: Is this a polygon? Why or why not? A: No… It is not made of line segments.

5. Q: Is this a polygon? Why or why not? A: No… Its sides do not intersect in exactly two places each.

6. Regular Polygons A regular polygon is a polygon whose sides are all the same length, and whose angles are all the same.

7. Vertex The vertex of an angle is the point where the two rays that form the angle intersect.

8. Vertex of a Polygon The vertices of a polygon are the points where its sides intersect.

9. Triangle A three-sided polygon.

10. Quadrilateral A four-sided polygon.

11. Pentagon A five-sided polygon. A regular pentagon:An irregular pentagon:

12. Hexagon A six-sided polygon. A regular hexagon:An irregular hexagon:

13. Heptagon A seven-sided polygon. A regular heptagon:An irregular heptagon:

14. Octagon An eight-sided polygon. A regular octagon:An irregular octagon:

15. Nonagon A nine-sided polygon. A regular nonagon: An irregular nonagon:

16. Decagon A ten-sided polygon. A regular decagon:An irregular decagon: