Exploring and Classifying Polygons

A video store has two membership plans. Plan A costs $15 to join and $2.50

per video. Plan B costs $20 to join and $1.75 per video. How many videos

must a customer rent before plan B is the better deal?

COURSE 1 LESSON 8-5

7 videos

8-5

In Lesson 8-4 You learned To classify triangles by

their angles and their sides.

What You Learned

Review

4.2.6 A.2 Quadrilaterals, including squares,

rectangles, parallelograms, trapezoids, rhombi

4.2.6 A.2 Polygons by number of sides

pg 380-383

Pg 122-123 Daily Notetaking Guide

Materials:

Standards:

Materials

In Lesson 8-5 To identify regular polygons and to

classify quadrilaterals.

What You’ll Learn

Why Learn This?

Signs have shapes to help you recognize them from

distances.

Introduction

8-5

Vocabulary 1 of 2

Polygon – is a closed figure that has three or more

line segments that do not cross.

Regular Polygon – a polygon with all sides

congruent and all angles congruent.

Irregular Polygon – is a polygon with sides that are

not all congruent or angles that are not all

congruent.

Quadrilateral – a polygon with four sides.

Vocabulary

Parallelogram – has two pairs of parallel sides.

Vocabulary 2 of 2

Trapezoid – has exactly one pair of parallel sides.

Rhombus – Parallelogram with four congruent sides.

Vocabulary

Square – parallelogram with four right angles and

four congruent sides.

Rectangle – a parallelogram with four right angles.

Pentagon – a polygon with five sides.

Hexagon – a polygon with six sides.

Octagon – a polygon with eight sides.

Decagon – a polygon with ten sides.

2. Name 2 segments skew to DE.

COURSE 1 LESSON 8-5

Exploring and Classifying Polygons

(For help, go to Lesson 8-1.)

1. Can parallel lines also be skew lines? Explain.

8-5

Check Skills You’ll Need

Vocabulary Review

No; skew lines are not in the same plane. No; skew lines

are not in the same plane.

segments not in the same plane as DE

: CB and GH

Identify each polygon according to the number of sides.

Exploring and Classifying Polygons

COURSE 1 LESSON 8-5

hexagon pentagon

b. a.

8-5

Quick Check

Determine whether each polygon is regular

or irregular.

Exploring and Classifying Polygons

COURSE 1 LESSON 8-5

a. No sides or angles are congruent. It is an

irregular polygon.

b. All sides and angles are congruent. It is a

regular polygon.

8-5

Quick Check

Exploring and Classifying Polygons

COURSE 1 LESSON 8-5

Write all the possible names for the quadrilateral.

Then give the best name.

Exactly one pair of opposite sides is parallel.

Its only possible name is a trapezoid.

8-5

Quick Check

How can you classify polygons?

By their number of sides.

What are the five special quadrilaterals that have

parallel sides?

Trapezoid, parallelogram, rectgangle, rhombus and

square.

Closure

Exploring and Classifying Polygons

Identify each polygon. Write all the possible names.

Determine if each polygon is regular or irregular.

1. 2.

3. 4.

COURSE 1 LESSON 8-5

octagon; regular hexagon; regular

quadrilateral, rhombus; irregular

parallelogram quadrilateral, trapezoid; irregular

8-5

Class work

Work

pg 389 – 390 1 - 32

Homework

pg 367 Practice 8-5

pg 368 Guided Problem Solving 8-5

Work