1

Bell Ringer: Geometry

Write down one thing you remember about parallelograms… wait for instructions as we’ll share our results in a few minutes on the board.

2

Daily Learning Target (DLT)

“I can understand, apply, and remember the sums of the measures of the interior and exterior angles of polygons.”

3

Bell Ringer: Geometry

Each student write down his or her one thing you remember about parallelograms on the whiteboard based on the parallelogram’s sides, angles, and diagonals.

4

Geometry: Reminders

1. Unit 7 Test this Friday (12/07/12)

2. All Unit 7 Work Due This Friday (12/07/12)

3. YOU HAVE TO STUDY… PLEASE DON’T PROCRASTINATE.

“Have you ever wondered what

the total number of degrees that

interior angles in a stop sign

add up to?”

NAMES OF POLYGONS

SIDES

TRIANGLE 3

QUADRILATERAL 4

PENTAGON 5

HEXAGON 6

HEPTAGON 7

OCTAGON 8

NONAGON 9

DECAGON 10

DODECAGON 12

N – GON N

Fist-To-Thumbs?

What is an Equilateral Polygon?

An equilateral polygon has all

sides congruent.

What is an Equiangular Polygon?

An equiangular polygon has all

angles congruent.

REGULAR POLYGONS

REGULAR POLYGONS

HAVE EQUAL SIDES AND

EQUAL ANGLES SO WE

CAN FIND THE MEASURE

OF EACH INTERIOR ANGLE

Fist-To-Thumbs?

INTERIOR ANGLE SUM

IF N IS THE NUMBER OF SIDES THEN:

INT ANGLE SUM =

(N – 2 ) 180°

INTERIOR ANGLE SUM

Find the interior sum of the angles of the Speed Limit sign.

INT ANGLE SUM =

(N – 2 ) 180°

INTERIOR ANGLE SUM

Find the interior sum of the angles of the Speed Limit sign.

INT ANGLE SUM =

(4 – 2 ) 180° = 360°

INTERIOR ANGLE SUM

Find the interior sum of the angles of the Pentagon.

INT ANGLE SUM =

(N – 2 ) 180°

INTERIOR ANGLE SUM

Find the interior sum of the angles of the Pentagon.

INT ANGLE SUM =

(5 – 2 ) 180° = 540°

Fist-To-Thumbs?

EACH INTERIOR ANGLE OF

A REGULAR POLYGON =

(N – 2 ) 180

N

REMEMBER N = NUMBER OF SIDES

REGULAR PENTAGON

Find the measures of one of the

interior angles.

(N – 2 ) 180

N

INT ANGLE SUM =

(5 – 2 ) 180 = 540°

EACH INT ANGLE =

540 = 108°

5

REGULAR PENTAGON

Find the measures of one of the

interior angles.

(N – 2 ) 180

N

REGULAR OCTAGON

Find the measures of one of the

interior angles.

REGULAR OCTAGON

Find the measures of one of the

interior angles.

INT ANGLE SUM =

(8 – 2 ) 180 = 1080°

EACH INT ANGLE =

1080 = 135°

8

Fist-To-Thumbs?

ALL POLYGONS HAVE AN EXTERIOR ANGLE SUM OF

360°

EXTERIOR ANGLE

EXTERIOR ANGLE SUM

THE MEASURE OF EACH EXTERIOR ANGLE OF A REGULAR POLYGON IS

360°

N

NAME ____________

# SIDES ____6________

INT ANGLE SUM _________

EACH INT ANGLE _________

EXT ANGLE SUM _________

EACH EXT ANGLE _ _____

NAME HEXAGON

# SIDES 360 / 60 = 6

INT ANGLE SUM (6-2) X 180 = 720°

EACH INT ANGLE 720 / 6 = 120°

EXT ANGLE SUM 360°

EACH EXT ANGLE 60

NAME ___________

# SIDES _____9_______

INT ANGLE SUM _________

EACH INT ANGLE _________

EXT ANGLE SUM _________

EACH EXT ANGLE _________

NAME NONAGON

# SIDES 9

INT ANGLE SUM (9-2) x 180 =

1260°

EACH INT ANGLE 1260 / 9 = 140°

EXT ANGLE SUM 360°

EACH EXT ANGLE 360 / 9 = 40°

Fist-To-Thumbs?

Next? Please write in a

sentence in the left or

right margin of your

notes to remember the

main idea.

Assignment

Work On The Polygon Puzzle Scramble

Closing – Formative

Assessment (Whiteboards)

Do on your own.

NAME __________

# SIDES _____10_______

INT ANGLE SUM _________

EACH INT ANGLE _________

EXT ANGLE SUM _________

EACH EXT ANGLE _________

NAME DECAGON

# SIDES _10__

INT ANGLE SUM (10-2) X 180 =

1440°

EACH INT ANGLE 1440 / 10 = 144°

EXT ANGLE SUM 360°

EACH EXT ANGLE 36