geometry 7.9 area of circles & sectors 14 3 sector of a circle - a region bounded by 2 radii of...
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Geometry_7.9_March 14
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warm-up after 7.8:
1. Find the radius. 2. Find the length of AB
3. Find m QR
Geometry 7.9 Area of Circles & Sectors
Learning Target:I can evaluate the area of circles & sectors. [G.C.5]
Geometry_7.9_March 14
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Area of a circle = π radius2
Area of a circle
** Remember to follow order of operations (do exponents before you multiply)
Acircle = π r2
The diameter of a circle is 11cm. Find the area. 1.
2. The area of a circle is 158.3 yd2. What is the diameter?
diameter = 2 x radius
= 14.2 yds
Geometry_7.9_March 14
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Sector of a Circle- A region bounded by 2 radii of the circle and their intercepted arc.
sector APB
Area of sector degrees in arc
Area of circle 360˚=
3. Find the area of the sectors formed by ∠HJK.H
˚
m
Area of Blue Sector
Area of Red Sector
Geometry_7.9_March 14
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4. Find the area of C.
5. Find the area of the shaded region.
6 ft
18 ft
3 circles in total
Area of circles = Ans.
Geometry_7.9_March 14
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Assignment:7.9 worksheet
Geometry Name ______________________________ Pd. ___ 7.9AreaofCircles&Sectors Findtheareaofthecirclewiththegiveninformation.Roundtonearesthundredth.Show all work!1.radius=5cm 2.diameter=16ft 3.circumference=72.22mArea=_____________ Area=_____________ Area=_____________Determinetheradiusofthecirclewiththegivenarea.Roundtonearesthundredth.Show all work!4.Area=25𝜋cm2 5.Area=48ft2 Radius=_____________ Radius=_____________Findtheareaoftheshadedsectors.Roundtonearesthundredth.Show all work!6. 7. 8. Area=_____________ Area=_____________ Area=_____________Usethediagramtofindtheindicatedmeasure.Roundtonearesthundredth.Show all work!9.Areaof⊙𝑀=_____________ 10.Areaof⊙𝑀=_____________ 11.Radius=_____________
Findtheareaoftheshadedregion.Roundtonearesthundredth.Show all work!12. 13. Area=_____________ Area=_____________ 14.Findthecircumference,arclength,areaofthecircleandareaofthesector.Show all work! Circumference=_________ArcLength=__________Areaof⊙=_____________Areaofsector=___________Review.15.Writetheequationofacirclewithcenter(6,–1)andradiusof10.________________________________________________16.Theequationofacircleis(x+4)2+y2=49.Thecenterwouldbe______________andtheradiuswouldbe________.Findthefollowingvalues.Show all work!17. 18.
x=_______ x=_______19. 20. 21.
x=_______
! mAB! =________˚ x=_______ y=_______
210˚
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Geometry 7.9 (Area of circles and sectors) Worksheet Answers1. 78.5 cm2 2. 200.96 ft2 3. (r ≈ 11.5) A ≈ 415.27 m2
4. 5 cm 5. 3.9 ft
6. 52.3 in2 7. 126.04 m2 8. 602.88 ft2
9. 84.02 m2 10. 66.04 cm2 11. (area ≈ 50) r ≈ 4 m
12. 21.5 cm2 13. 220.16 cm2
Area of Square – Area of Circle Area of Square – Area of 16(Circles)
14. C = 37.68 ft, arc length = 21.98 ft,
Area of ⨀ = 113.04 ft2, Area sector = 65.94 ft2
15. (x – 6)2 + ( y + 1)2 = 100
16. (–4, 0), r = 7
17. 110˚ 18. 14
19. 120˚ 20. 61˚ 21. x = 26, y =48