11.2 Area of Circles and Sectors with work
1
Core Concept
How can you find the area of a sector of a circle?
11.2 Area of Circles and Sectors
Mar 610:41 AM
Example 1: Find each indicated measure.
a. area of a circle with a radius of 8.5 inches b. diameter of a circle with an area of 153.94 square feet
Practice:
1. Find the area of a circle with a radius of 4.5 meters.
2. Find the radius of a circle with an area of
176.7 square feet.
11.2 Area of Circles and Sectors with work
2
a. About 124,000 people live in a 2mile radius of a city’s post office. Find the population density in people per square mile.
b. A region with a 10mile radius has a population density of about 869 people per square mile. Find the number of people who live in the region.
Example 2:
Mar 610:57 AM
Practice:
3. About 58,000 people live in a region with a 2mile radius. Find the population density in people per square mile.
4. A region with a 3mile radius has a population density of about 1000 people per square mile. Find the number of people who live in the region.
11.2 Area of Circles and Sectors with work
3
Example 3: a. b.
Practice: Find the indicated measure.
5. area of red sector
6. area of blue sector
7. A rectangular wall has an entrance cut into it. You want to paint the wall. To the nearest square foot, what is the area of the region you need to paint?
11.2 Area of Circles and Sectors with work
4
Feb 156:24 PM
Example 4: Find the area of each shaded region.
5 in
a) b)
Feb 151:41 PM
16
Answer: 100.5 mm2
Practice 8: Find the shaded area. Give exact answers AND approximations.
mm
11.2 Area of Circles and Sectors with work
5
Mar 611:02 AM
HW: p. 606
A: 19, 21, 27, 29, 31, 35, 37, 42 45
B: 1, 3, 7, 9, 13, 17, 19, 21, 27, 29, 31, 42 45
C: 1 31 (o), 42 45
ANSWERS:
42. 54 in.2
44. 58.5 in.2
Attachments
Area of a circle.gsp
SMART Notebook
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