Download 3-4 The Polygon Angle-Sum Theorem M11.B.2 2.3.11.B Objectives


A Polygon is a closed plane figure with at
least three sides. The sides intersect only at
their endpoints, and no adjacent sides are
collinear.
A.
B.
C.



Identify the vertices
Identify the sides
Identify the angle
To name a polygon, start
with any vertex and list the
vertices consecutively.


COPY the blue table from page 144 into your
notebooks.

A convex polygon has no diagonal with
points outside the polygon.

A concave polygon has at least one diagonal
with points outside the polygon.

Classify each polygon by its sides. Identify
each as either convex or concave.
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
The sum of the measures of the angles of an
n-gon is:
Sum = (n-2)180
n = number of sides
PROOF - Triangle

A.

B. The sum of a decagon

Find m<A in pentagon ABCDE

The sum of the measures of the exterior
angles of a polygon, one at each vertex, is
360.


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Equilateral Polygon – all sides congruent.
Equiangular Polygon – all angles congruent
Regular Polygon – both equilateral and
equiangular.

Find the measure of an interior angle and an
exterior angle of each REGULAR polygon.