Partner Vocabulary NotesPartner Vocabulary Notes

Share a copy of Buckle Down, Page 163-164

Complete foldable with vocabulary word, definition and picture.

10 minutes

““Parts of a Circle” OrganizerParts of a Circle” Organizer

Create a class poster with all parts of the circle labeled. (see next slides)

DIAMETERDIAMETER

DIAMETER is the distance through the CENTER of the circle.

It is twice as large as the radius.

d =diameterr= radius

RadiusRadius

Radius is ½ as large as the diameter.

•R=1/2d

Parts of a Circle…Parts of a Circle…

Circumference Circumference

Circumference is the distance around the circle.

To find the circumference of a circle, you have to know the diameter or radius.

PIPI

Pi is…the ratio of the circumference to the diameter.

Diameter

radi

usThe circumference of a circle is the distance around the outside

The area of a circle is the space inside it

The circumference is found using the formula:

C=πd or C= 2rπ

(since d=2r)

The area is found using the formula

A= π r2

BEFORE WE BEGIN FINDING CIRCUMFERENCE AND AREA, YOU MUST REMEMBER THIS…

For every problem, you must show:

The Formula

The Substitutions

Final Answer

Labeling

The diameter of the quarter is 5.5cm.

What is the circumference?

What is the area?

AND THE ANSWER IS…..AND THE ANSWER IS…..

approx 17.27 cm

circumferenceapprox. 23.74625 cm2

Area

Why Why “APPROXIMATELY“APPROXIMATELY

”?”?

The diameter of the circle is 8cm.

What is the circumference?

What is the area?

AND THE ANSWER IS…..AND THE ANSWER IS…..

approx. 25.12 cm circumference

approx. 50.24 cm2 Area

The radius of the circle is 2cm.

What is the circumference?

What is the area?

AND THE ANSWER IS…..AND THE ANSWER IS…..

approx. 12.56 cm circumference

approx. 12.56cm2 Area

A pizza place has an 8” diameter, 12” diameter, and a 16” diameter pizza. What is the area and circumference of those pizzas?

AND THE ANSWERS ARE (approximately)AND THE ANSWERS ARE (approximately)…..…..

8” Pizza:circumference: 25.12” area: 50.24 in2

12” Pizza:circumference: 37.68”area: 113.04 in2

16” Pizza:circumference: 50.24”area: 200.96 in2

The area of a circle is 78.5 square meters. What is the radius?

AND THE ANSWER IS…..AND THE ANSWER IS…..

Radius = 5 meters approximately

The circumference of a circle is 15.7 centimeters. What is the diameter?

AND THE ANSWER IS…..AND THE ANSWER IS…..

Diameter = 5 cm approximately

Independent PracticeIndependent Practice

Buckle Down

Page 165-166

All problems

Homework if not complete

Using Circumference Formula and Using Circumference Formula and Area of a Parallelogram for Area of Area of a Parallelogram for Area of a Circlea Circle

Buckle Down

Page 164

Use Paper Plates or segmented circle to demonstrate

If time…If time…

Sir Cumference and the Round Table