lesson 10-7 pages 533-538 circumference and area: circles

25
Lesson 10-7 Pages 533-538 Circumference and Area: Circles

Upload: octavia-warren

Post on 31-Dec-2015

225 views

Category:

Documents


1 download

TRANSCRIPT

Page 1: Lesson 10-7 Pages 533-538 Circumference and Area: Circles

Lesson 10-7 Pages 533-538

Circumference and Area: Circles

Page 2: Lesson 10-7 Pages 533-538 Circumference and Area: Circles

What you will learn!1. How to find the circumference of circles.

2. How to find area of circles.

Page 3: Lesson 10-7 Pages 533-538 Circumference and Area: Circles

CircleCircle

DiameterDiameter

CenterCenter

CircumferenceCircumference

RadiusRadius (pi)(pi)

Page 4: Lesson 10-7 Pages 533-538 Circumference and Area: Circles

What you really need to know!

A circle is the set of all points in a plane that are the same distance from a given point.

Page 5: Lesson 10-7 Pages 533-538 Circumference and Area: Circles

What you really need to know!

The ratio of the circumference of a circle to its diameter is always equal to 3.1415926... The Greek letter (pi) stands for this number. Using this ratio, you can derive a formula for the circumference of a circle.

d

c dc

Page 6: Lesson 10-7 Pages 533-538 Circumference and Area: Circles

What you really need to know!

dc

rc 2

Page 7: Lesson 10-7 Pages 533-538 Circumference and Area: Circles

What you really need to know!

The area A of a circle equals the product of pi () and the square of its radius r. A = r2

Radius

Page 8: Lesson 10-7 Pages 533-538 Circumference and Area: Circles
Page 9: Lesson 10-7 Pages 533-538 Circumference and Area: Circles

r

½ of the circumference

½ of 2r

rrA 22

1 2rA

Page 10: Lesson 10-7 Pages 533-538 Circumference and Area: Circles
Page 11: Lesson 10-7 Pages 533-538 Circumference and Area: Circles
Page 12: Lesson 10-7 Pages 533-538 Circumference and Area: Circles

Example 1:

Find the circumference of the circle to the nearest tenth.

C = d

C = x 12

C = 37.7 in

Page 13: Lesson 10-7 Pages 533-538 Circumference and Area: Circles

Example 2:

Find the circumference of the circle to the nearest tenth.

C = d

C = x 14.2

C = 44.6 m

Page 14: Lesson 10-7 Pages 533-538 Circumference and Area: Circles

Example 3:

A landscaper has a tree whose roots form a ball-shaped bulb with a circumference of about 110 inches. How wide will the landscaper have to dig a hole in order to plant the tree?

Page 15: Lesson 10-7 Pages 533-538 Circumference and Area: Circles

Example 3:

C = d

110 = •d

35.01408748 = d

At least 35 inches!

Page 16: Lesson 10-7 Pages 533-538 Circumference and Area: Circles

Example 4:

Find the area of the circle to the nearest tenth.

A = r2

A = x 112

A = 380.1 ft2

Page 17: Lesson 10-7 Pages 533-538 Circumference and Area: Circles

Example 4:

Find the area of the circle to the nearest tenth.

A = r2

A = x 4.152

A = 54.1 cm2

Page 18: Lesson 10-7 Pages 533-538 Circumference and Area: Circles

Page 535-536

Guided Practice

#’s 4-9

Page 19: Lesson 10-7 Pages 533-538 Circumference and Area: Circles
Page 20: Lesson 10-7 Pages 533-538 Circumference and Area: Circles

Pages 533-535 with someone at home and

study examples!

Read:

Page 21: Lesson 10-7 Pages 533-538 Circumference and Area: Circles

Homework: Pages 536-538

#’s 10-30 even

#’s 37, 38, 48-53

Practice Quiz 2 #’s 1-5Lesson Check 10-7

Page 22: Lesson 10-7 Pages 533-538 Circumference and Area: Circles
Page 23: Lesson 10-7 Pages 533-538 Circumference and Area: Circles
Page 24: Lesson 10-7 Pages 533-538 Circumference and Area: Circles
Page 25: Lesson 10-7 Pages 533-538 Circumference and Area: Circles

Page

749

Lesson 10-7