10.7 Areas of Circles and Sectors 2011
March 08, 2011
1. FInd the circumference
2. Find the measure of Abc
(
(
Warm­up
3. Find the length of xy
o
b
112
4.5
7
101o
c
a
Feb 24­2:16 PM
1
10.7 Areas of Circles and Sectors 2011
March 08, 2011
Challenge Problem
8 ft
10 ft
Apr 21­8:04 AM
2
10.7 Areas of Circles and Sectors 2011
March 08, 2011
10­7: Areas of Circles, Sectors, and Segments.
Objective: Find the area of circles, sectors, and segments.
Apr 20­12:26 PM
3
10.7 Areas of Circles and Sectors 2011
March 08, 2011
Refresher
How do you find the circumference of a circle?
How do you find the area of a circle?
Apr 20­2:29 PM
4
10.7 Areas of Circles and Sectors 2011
March 08, 2011
New Vocabulary: SECTOR
A sector is a region bounded by two radii of a circle.
X
The blue shaded region is called sector XOY.
O
Y
How can we find the area of a sector if we know the measure of XOY ?
Apr 20­2:32 PM
5
10.7 Areas of Circles and Sectors 2011
March 08, 2011
Apr 21­7:32 AM
6
10.7 Areas of Circles and Sectors 2011
March 08, 2011
Find the area of sector ZOM.
A circle has a diameter of 20 cm. What is the area of a sector bounded by a 208o major arc?
Apr 21­7:37 AM
7
10.7 Areas of Circles and Sectors 2011
March 08, 2011
New Vocabulary: SEGMENT
A part of a circle bounded by an arc and the segment joining its endpoints is a segment of a circle.
Segment of a circle.
Apr 21­7:45 AM
8
10.7 Areas of Circles and Sectors 2011
March 08, 2011
How do we find the area of segment AB given the measure of AOB and the radius ?
A
O
B
Apr 21­7:51 AM
9
10.7 Areas of Circles and Sectors 2011
March 08, 2011
Area of a segment
Apr 21­7:56 AM
10
10.7 Areas of Circles and Sectors 2011
March 08, 2011
Find the area of segment AB.
Apr 21­7:59 AM
11
10.7 Areas of Circles and Sectors 2011
March 08, 2011
Practice
A circle has a radius of 12 cm. Find the area of the smaller segment of the circle bounded by a 60o arc.
Apr 21­8:01 AM
12
10.7 Areas of Circles and Sectors 2011
March 08, 2011
Homework
pg 577 # 1, 3, 7­19 even,
23, 26, 30
Apr 21­8:15 AM
13
10.7 Areas of Circles and Sectors 2011
March 08, 2011
Mar 8­2:40 PM
14