POLYGONS POLYGONS A close plane figure bounded by

POLYGONS

POLYGONS - A close plane figure bounded by a straight lines. - in geometry, a simple closed twodimensional figure formed by the joining of three or more straight line segments, called sides.

POLYGONS �All polygons have an equal number of sides and vertices, and the sum of the interior angles of a polygon with n sides is 180° × (n – 2). If the sides of a polygon are of equal length and the angles are equal, the polygon is regular; otherwise it is irregular.

� Regular Polygon Irregular Polygon

POLYGONS �Polygons are either convex or concave. Every interior angle of a convex polygon is less than 180°, while at least one angle of a concave polygon is greater than 180°. An easy way to tell if a polygon is convex is to lay a ruler along each side in turn. If the ruler never juts into the inside of the polygon, the polygon is convex.

CONVEX CONCAVE

PARTS OF A POLYGON 1. Sides 2. apothem - distance from the center of a regular polygon to a side.

EXAMPLES OF COMMON POLYGONS: �Triangle = geometric figure consisting of three points, called vertices, connected by three sides.

EXAMPLES OF COMMON POLYGONS: �Square = two-dimensional figure with four straight sides, whose four interior angles are right angles (90°), and whose four sides are of equal length.

EXAMPLES OF COMMON POLYGONS: �Rectangle = quadrilateral (four-sided plane figure) with opposite sides equal and parallel and with each interior angle a right angle (90°).

OTHER POLYGONS: Pentagon = with five sides

OTHER POLYGONS: Hexagon = with six side polygon

OTHER POLYGONS: Heptagon – a polygon with seven sides. Octagon – Polygon with eight sides. Nonagon – with nine sides. Decagon – with ten sides.

�Thanks For Listening… � References: Geometry Book III Encarta

�Please Prepare for a long Quiz Tommorow…