Sec 1-6 Classify Polygons

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Transcript Sec 1-6 Classify Polygons

Sec 1-6 Concept: Polygons Objective: Given a figure, we will identify and name it if it is a polygon as measured by a scoring guide

Vocabulary:

Polygon:

a plane figure that meets these 2 criteria 1. It is formed by three or more line segments called sides 2. each side intersects exactly two sides, one at each endpoint, so that no two sides with a common endpoint are collinear.

Vertex N O Polygon SNOW S W

A Example 1: Determine which shapes are polygons. If a shape is a polygon, then state if it is concave or convex.

B C D A - yes B - no C - yes D - yes concave concave convex

Names of Polygons: Handout

You have 10 min. to do this handout, then we will go over it

Regular Polygon:

A regular polygon is both

equilateral

and

equiangular

Example 2: Each figure is a regular polygon. Expressions are given for two sides lengths. Find the value of x.

x 2 +5x+13 7x+34 11x-14 7x+34 = 11x-14 48=4x 12=x x 2 +10x-7 x 2 +5x+13 = x 2 +10x-7 20=5x 4=x

Example 3: The expressions (3x+63)° and (7x-45)° represent the measures of two angles of a regular decagon. Find the measure of an angle of the decagon.

3x+63=7x-45 108=4x 27=x 3(27)+63 =144°

Example 4: Draw a figure that fits the description.

1.

A quadrilateral that is not regular 2.

A concave pentagon

Example 5 # 31 p. 46

Example 6 # 33 & 36 p. 46

Today’s Work: