warm up - westbranch.k12.oh.us · geo.1.06.16sec.5.8.notebook january 06, 2016 sector of a circle a...
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Geo.1.06.16sec.5.8.notebook January 06, 2016
Warm Up1. Find the circumference of a circle with a radius of 8 ft. Leave your answer in terms of π .
A. 4π ft.B. 8π ft.C. 16π ft. D. 64π ft.
2. Calculate the length of arc AB.
A. 7.64π cm
B. 2.43π cm
C. 4.87π cm
D. 15.29π cm
Geo.1.06.16sec.5.8.notebook January 06, 2016
3.
A. 176.8 cm
B. 596.9 cm
C. 41.5 cm
D. 555.5 cm
HW Solutionsp. 28283#913, 1922
9. 28π, 3.5π10. 24π, 8π11. 36π, 27π12. 36π, 33π13. a. 100 b. 50 c. 100π/3
19. 36.1320. 16.1021. 3.9322. 8.17
Geo.1.06.16sec.5.8.notebook January 06, 2016
5-8 Areas of Circles, Sectors, and Segments of Circles
Objective: Compute the areas of circles, sectors, and segments of circles.
Area of a circle video
Geo.1.06.16sec.5.8.notebook January 06, 2016
Theorem 5-12Area of a CircleThe area of a circle is the product ofπ and the square of the radius.
Find the area of ¤K in terms of π.
Example:
Geo.1.06.16sec.5.8.notebook January 06, 2016
Sector of a Circle a region bound by two radii and their intercepted arc** A slice of pizza is an example of a sector of a circle.
** A sector is named using one endpoint of the arc, the center of the circle, and the other endpoint of the arc
The area of a sector is a fraction of the circle containing the sector.
To find the area of a sector whose central angle measures m°, multiply the area of
the circle by m360
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Geo.1.06.16sec.5.8.notebook January 06, 2016
sector ABC
Find the area of each sector. Give answers in terms of π and rounded to the
nearest hundredth.
Geo.1.06.16sec.5.8.notebook January 06, 2016
Find the area of each sector. Give answers in terms of π.
sector HGJA. 8.73πB. 52.4πC. 144πD. 209.6π
Now back to that pizza! What is the area of one slice of pizza if the diameter of the pizza is 16 inches?
A. 32π
B. 2π
C. 64π
D. 8π
Geo.1.06.16sec.5.8.notebook January 06, 2016
Jan 68:33 AM
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HW # 53p. 288 # 1-6, 8-17
Geo.1.06.16sec.5.8.notebook January 06, 2016
You can use the circumference of a circle to find its area. Divide the circle and rearrange the pieces to make a shape that resembles a
parallelogram.
The base of the parallelogram is about half the circumference, or πr, and the height is close to the radius r. So A ≅ π r · r = π r2.
The more pieces you divide the circle into, the more accurate the estimate will be.