1. Warm up for Section 4.8

2. Answers to Warm up for Section 4.8
C ≈ ft
65.98 = 2r
65.98/(2) = r
10.50 cm ≈ r
Length AB
= 150
360
≈ in.
∙ 2(18)

3. °
in cm
π ≈ mm
4.7 Homework Answers

4. Area of a Circle and a Sector
Section 4.8
Standard: MM2G3 cd
Essential Question: How do I find the area of a
sector using the measure of a central angle?

5. Before beginning this section, you must remember a
few formulas that you have learned in the past:
The area of a circle is given by the formula:

6. A sector is the region bounded by two radii of the
circle and their intercepted arc. It is a portion of the
entire area.

7. A is the center of the circle at right.6
40˚
What is the total area of the circle?
We will use this information to find the area of the
shaded sector. The formula for the area of a sector
is very similar to the formula for arc length.

8. The formula for the area of a sector is given by:
Using the formula above, we can determine the
area of the shaded sector. A 6
40˚

9. Find the area of circle Y. Area of circle = AX
Area of shaded
Sector = 95 cm2 Y
150˚ Z
The area of the circle is 228 cm2.

10. Find the area of both sectors.
Area of circle =
21 mm
Area small sector:
110˚ B C
Area large sector:

11. The small sector has area 423.33 mm2 and the
110˚ B C
The small sector has area mm2 and the
large sector has area mm2.

12. Find the area of circle H. Area of circle = A F
70˚ G H
Area of shaded
region is m2
The area of circle H is m2.