1.6 – Two-1.6 – Two-Dimensional Dimensional

FiguresFigures

PolygonsPolygons• A polygon is a closed figure formed

by sides.

• The vertex of each angle is a vertex

of the polygon.

• A polygon is named by the letters of

its vertices, written in order of

consecutive vertices.

PolygonsPolygons Not Polygons

Concave Concave PolygonsPolygons

Contains vertices in the interior of the polygon. If you were to draw lines containing each side of the polygon there would be lines crossing through

the interior of the polygon.

Convex PolygonsConvex Polygons

No vertices are in the interior of the polygon.

If you draw lines containing the sides there would be no

points in the interior.

Number of Sides Polygon

3 Triangle

4 Quadrilateral

5 Pentagon

6 Hexagon

7 Heptagon

8 Octagon

9 Nonagon

10 Decagon

11 Hendecagon

12 Dodecagon

N N-gon

An equilateral polygon is a polygon in which all sides are congruent.

An equiangular polygon is a polygon in which all angles are congruent.

A convex polygon that is both equilateral and equiangular is called a regular polygon.

Name each polygon by its number of sides. Then classify it as convex or concave and regular or irregular. A.) B.)

C.) D.)

• The perimeterperimeter of a polygon is the sum of the lengths of the sides of the polygon.

• The circumferencecircumference of a circle is the distance around the circle.

• The areaarea of a figure is the number of square units needed to cover a surface.

b

dc

h

s

s

w

l

d

r

Find the perimeter or circumference and area of each figure.

A.)

3.2 cm

2.1 cm

B.) 3in.

C.)

6 ft.

D.)

9.5 in. 9.5

in.

10.2 in.

8 in.