7-5 Polygons

7-5 Polygons
Learn to identify and name polygons.
Course 2
7-5 Polygons
Insert Lesson Title Here
Vocabulary
polygon
side
vertex of a polygon
regular polygon
Course 2
7-5 Polygons
Triangles and rectangles are examples of
polygons. A polygon is a closed plane figure
formed by three or more line segments. Each
line segment forms a side of the polygon, and
meets, but does not cross, another line
segment at a common point. This common point
is a vertex of a polygon.
Side
The polygon at
left has six
sides and six
Vertex
vertices.
Remember!
Vertices is plural for vertex.
Course 2
7-5 Polygons
Additional Example 1A & 1B: Identifying Polygons
Determine whether each figure is a polygon. If
it is not, explain why not.
A.
The figure is a
polygon. It is a
closed figure with
4 line segments.
Course 2
B.
The figure is not a
polygon. It is not a
closed figure.
7-5 Polygons
Additional Example 1C & 1D: Identifying Polygons
Determine whether each figure is a polygon. If
it is not, explain why not.
C.
The figure is not a
polygon. The
figure is not
formed by line
segments.
Course 2
D.
The figure is not a
polygon. There are
line segments in
the figure that
cross.
7-5 Polygons
Try This: Example 1A & 1B
Determine whether each figure is a polygon. If
it is not, explain why not.
A.
The figure is a
polygon. It is a
closed figure with
5 line segments.
Course 2
B.
The figure is not a
polygon. It is not a
closed figure.
7-5 Polygons
Try This: Example 1C & 1D
Determine whether each figure is a polygon. If
it is not, explain why not.
C.
The figure is not a
polygon. The
figure is not
formed by line
segments.
Course 2
D.
The figure is not a
polygon. There are
line segments in
the figure that
cross.
7-5 Polygons
Polygons are classified by the number of sides
and angles they have.
Triangle
3 sides
3 angles
Heptagon
7 sides
7 angles
Course 2
Quadrilateral
4 sides
4 angles
Octagon
8 sides
8 angles
Pentagon
5 sides
5 angles
Nonagon
9 sides
9 angles
Hexagon
6 sides
6 angles
Decagon
10 sides
10 angles
7-5 Polygons
Additional Example 2: Classifying Polygons
Name each polygon.
A.
B.
Octagon
Course 2
Quadrilateral
7-5 Insert
Lesson Title Here
Polygons
Try This: Example 2
Name each polygon.
B.
A.
Quadrilateral
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Pentagon
7-5 Insert
Lesson Title Here
Polygons
A regular polygon is a polygon in
which all sides are congruent and all
angles are congruent.
Course 2
7-5 Polygons
Additional Example 3: Identifying and Classifying
Regular Polygons
Name each polygon and tell whether it is a
regular polygon. If it is not, explain why not.
A.
The figure is a regular
quadrilateral. A regular
quadrilateral is also
called a square.
Course 2
B.
The figure is a
quadrilateral. It is not a
regular polygon because
all of the sides are not
congruent.
7-5 Insert
Lesson Title Here
Polygons
Try This: Example 3
Name each polygon and tell whether it is a
regular polygon. If it is not, explain why not.
A.
B.
The figure is a triangle. It is
The figure is a regular
not a regular polygon because triangle.
all sides and angles are not
congruent.
Course 2
7-5 Polygons
Insert Lesson Title Here
Lesson Quiz
Determine whether each statement is true or
false.
1. Every polygon is a closed figure. true
2. Every open figure is a polygon. false
3. A pentagon with sides lengths of 10 units and
angles measuring 108° is a regular polygon. true
4. A quadrilateral with side lengths of 10, 12, 10, and
12 units is a regular polygon. false
5. What is the name of a five-sided polygon? pentagon
Course 2
Homework
7-5 Worksheet