Download Two-Dimensional Figures

Two-Dimensional
Figures
Geometry
Ms. Hough
1-6
Vocabulary
A polygon is a closed figure whose sides
are all segments. A polygon’s sides
intersect exactly two other sides, but only
at their endpoints.
 Examples:

Convex or Concave

A Polygon is concave if any side can be
extended so that it appears in the interior
of the polygon.

A polygon is convex if the sides can be
extended and does not intersect the
interior of the polygon.
Number of Sides
3
4
5
6
7
8
9
10
12
n
Polygon Name
Triangle
Quadrilateral
Pentagon
Hexagon
Heptagon
Octagon
Nonagon
Decagon
Dodecagon
n-gon

A regular polygon is a convex polygon in
which all sides and angles are congruent.

You are now able to classify polygons with
three categories
 Name
 Concave/Convex
 Regular/Irregular
Give it a try



To find the perimeter of a polygon find the
SUM of the length of every side.
Example

Refer to
PQR with vertices P(-1,3), Q(-3, -1)
and R(4, -1)
a) Find the Perimeter of
b) Find the area of
PQR
PQR
Class Work

Complete the work sheet handed out.
Make sure to explain your reasoning for
your classifications, and SHOW YOUR
WORK for the remaining problems. This
will be collected and graded tomorrow.

When you are finished, go to
GeometryOnline.com and complete the
Vocabulary Review