A polygon is a closed plane figure bounded by three or more straight sides that meet at vertices. It comes from Greek words meaning "many" and "angles." A polygon has sides, vertices, diagonals, interior angles, and exterior angles. Polygons are classified as convex if lines containing sides do not cross the interior, or concave if lines cross the interior. Polygons are equilateral if all sides are equal, equiangular if all angles are equal, or regular if they are both equilateral and equiangular. Common polygons include octagons with 8 sides, dodecagons with 12 sides, hendecagons with 11 sides, and pentagons with 5 sides.

3. Prepared by:
Louchil V. Pizon

4.  A closed plane figure bounded by three or more
straight sides that meet in pairs in the same number
of vertices, and do not intersect other than at these
vertices.
 Comes from Greek word “poly” means many and
“gon” means angles.
Polygon

5.  A union of non-collinear segments, the sides, on a plane
that meet at their end points, the vertices, so that the
endpoint is contained by exactly two segments.
Polygon

6. Parts of a Polygon
o The side of the polygon is called as the surface of
polygon.
o The vertex of a polygon is the connection between
two sides.
o The diagonal is known as a line that connects two
points in the boundary of a polygon through the
centre.

7. o The interior angle is the angle that is
formed inside the polygon by two
adjacent sides.
o The exterior angle is the angle formed by
two adjacent sides, outside the polygon
by extending one of the sides of the
polygon.
Parts of a Polygon

8. Classification of a Polygon
 Convex Polygon- if lines containing the sides of the polygon
do not cross the interior of the polygon.
 Concave Polygon- if there are two points somewhere inside it for
which a segment with these as its endpoints cuts at least 2 of the
sides of the polygon

9. Classification of a Polygon

10. Type of Polygons
Equilateral Polygon- all sides are equal.
Equiangular Polygon- all angles are equal.
Regular Polygon- both equilateral and equiangular.

11. Activity
Recall:
1)A polygon is________________________________.
2)A polygon is equilateral if _____________________.
3)A polygon is equiangular if ____________________.
4)A polygon is regular if________________________.
Determine:
1)Polygon having 8 sides. ______________________
2)Polygon having 12 sides. _____________________
3)Polygon having 11 sides. _____________________
4)Polygon having 5 sides. ______________________

13. Reference:
Mathematics Learner’s Module I