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5-9 Honors Geometry Warm-up

5-9 Honors Geometry Warm-up. Find the area of the shaded region if AB= BC= CD. A. B. C. D. A bakery sells single-layer mini-cakes that are 3 inches in diameter for $4 each. They also have a 9-inch cake for $15. Which cake is more economical?. HW: p.613 #8-22even, p. 615 #39-42.

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5-9 Honors Geometry Warm-up

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  1. 5-9 Honors Geometry Warm-up Find the area of the shaded region if AB= BC= CD. A B C D

  2. A bakery sells single-layer mini-cakes that are 3 inches in diameter for $4 each. They also have a 9-inch cake for $15. Which cake is more economical?

  3. HW: p.613 #8-22even, p. 615 #39-42 • 391.1 in2 • 576 cm2 • 104.0 in2 14. 114.2 units2 • 4.1 units2 18. 56.9 units2 20. 54.4 in2 22. 168.2 units2 39. 34.6 units2 40. 68.7 units2 41. 157.1 units2 42. 7.7 units2

  4. r a p Use this formula if you know the perimeter or side length of the polygon: A = p²× q tan(180 ÷ q) Neel's Apothem Formulas • Spending too much time on those pesky area-of-a-polygon problems? Well, it’s your lucky day. • These formulas work for any regular polygon (even a polygon that isn’t inscribed.) • In the below formulas, • A = the area of the polygon • a= the length of the apothem • q = the number of sides of the polygon • p = the length of half a side of the polygon (or, Perimeter ÷ 2q) • r = the distance from the center of the polygon to any vertex (in inscribed polygons, this is the radius of the circle) • So the basic formula is: • A = a × p × q • Use this if you know the area but have to find one of the other measures. Use this formula if you know the length of the apothem of the polygon: A = a²× q × tan(180 ÷ q) Use this formula if you know the length of the radius: A = r²× q × sin(180 ÷ q) × cos(180 ÷ q)

  5. 1. A regular pentagon with a side length of 10 inches. • 2. A square with a radius of inches. • 3. A regular octagon with perimeter of 80 inches. • 4. A regular pentagon with an apothem of 7.5 meters.

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