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Warm Up


A complement of an angle is five times as large as
the angle. Find the angles.
The measure of one of two complementary angles
is six less than twice the measure of the other.
Find the angles.
Classifying Polygons
Objective:
Students will identify and name polygons.
Perimeter of polygons will also be found.
Polygons

A polygon is a closed figure formed
by coplanar segments such that:



The sides that have a common
endpoint are NOT collinear
Each side intersects exactly 2 other
sides, but ONLY at their endpoint
A polygon is named by the letters of
its vertices written in CONSECUTIVE
order.
Convex or Concave?
Concave polygons
have some of the
lines passing
through the
interior of the
figure.

Convex polygons
have no points of
the lines in the
interior of the
figure.
Regular or Irregular?


A convex polygon in
which all the sides are
congruent and all the
angles are congruent is
a regular polygon.
Otherwise, the polygon
is irregular.
Names of Polygons
Number of Sides
Polygon Name
3
4
5
6
7
8
9
10
12
n
Triangle
Quadrilateral
Pentagon
Hexagon
Heptagon
Octagon
Nonagon
Decagon
Dodecagon
N-gon
Perimeter



The perimeter of a polygon is the
sum of the lengths of its sides.
Find the perimeter:
Find x:
Classify the polygon

Name the polygon by its number of sides.
Then classify it as convex or concave and
regular or irregular.