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Warm Up

Warm Up. 1. Find the surface area of a square pyramid whose base is 3 m on a side and whose slant height is 5 m. 2. Find the surface area of a cone whose base has a radius of 10 in. and whose slant height is 14 in. Use 3.14 for  . 39 m 2. 753.6 in 2. Spheres. 6.10. Pre-Algebra.

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Warm Up

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  1. Warm Up 1. Find the surface area of a square pyramid whose base is 3 m on a side and whose slant height is 5 m. 2. Find the surface area of a cone whose base has a radius of 10 in. and whose slant height is 14 in. Use 3.14 for . 39 m2 753.6 in2

  2. Spheres 6.10 Pre-Algebra

  3. Learn to find the volume and surface area of spheres.

  4. Vocabulary sphere hemisphere great circle

  5. A sphere is the set of points in three dimensions that are a fixed distance from a given point, the center. A plane that intersects a sphere through its center divides the two halves or hemispheres. The edge of a hemisphereis agreat circle.

  6. The volume of a hemisphere is exactly halfway between the volume of a cone and a cylinder with the same radius r and height equal to r.

  7. 4 3 V = pr3 = p(9)3 4 3 Example: Finding the Volume of a Sphere Find the volume of a sphere with radius 9 cm, both in terms of p and to the nearest tenth of a unit. Volume of a sphere Substitute 9 for r. = 972p cm3 3,052.1 cm3

  8. 4 3 V = pr3 = p(3)3 4 3 Try This Find the volume of a sphere with radius 3 m, both in terms of p and to the nearest tenth of a unit. Volume of a sphere Substitute 3 for r. = 36p cm3 113.0 m3

  9.  50.3 units2 The surface area of a sphere is four times the area of a great circle.

  10. Example: Finding Surface Area of a Sphere Find the surface area, both in terms of p and to the nearest tenth of a unit. Surface area of a sphere S = 4pr2 = 4p(32) Substitute 3 for r. = 36p in2 113.0 in2

  11. 1738 km Try This The moon has a radius of 1738 km. Find the surface area, both in terms of p and to the nearest tenth. S = 4pr2 Surface area of a sphere = 4p(17382) Substitute 1738 for r. = 12,082,576p km2  37,939,288.6 km2

  12. V = pr3 = p(423) 22 7  74,088 4 3 4 3 4 3 Example: Comparing Volumes and Surface Areas Compare the volumes and surface areas of a sphere with radius 42 cm with that of a rectangular prism measuring 44 cm  84 cm  84 cm. Rectangular Prism: Sphere: V = lwh = (44)(84)(84) 310,464 cm3 =310,464 cm3

  13. 22 7 S = 2(44)(84) + 2(44)(84)  7,056  22,176 cm2 + 2(84)(84) Example Continued Compare the volumes and surface areas of a sphere with radius 42 cm with that of a rectangular prism measuring 44 cm  84 cm  84 cm. Rectangular Prism: Sphere: S = 4pr2 = 4p(422) S = 2lw + 2lh + 2wh = 7,056p = 28,896 cm2 The sphere and the prism have approximately the same volume, but the prism has a larger surface area.

  14. V = pr3 = p(213) 22 7  9261 4 3 4 3 4 3 Try This Compare the volume and surface area of a sphere with radius 21 mm with that of a rectangular prism measuring 22  42  42 mm. Rectangular Prism: Sphere: V = lwh = (22)(42)(42) 38,808 mm3 =38,808 mm3

  15. 22 7 S = 2(22)(42) + 2(22)(42)  1764  5544 mm2 + 2(42)(42) Try This Continued Compare the volume and surface area of a sphere with radius 21 mm with that of a rectangular prism measuring 22  42  42 mm. Rectangular Prism: Sphere: S = 4pr2 = 4p(212) S = 2lw + 2lh + 2wh = 1764p = 7224 mm2 The sphere and the prism have approximately the same volume, but the prism has a larger surface area.

  16. Lesson Quiz: Part 1 Find the volume of each sphere, both in terms of  and to the nearest tenth. Use 3.14 for p. 1.r = 4 ft 2.d = 6 m Find the surface area of each sphere, both in terms of  and to the nearest tenth. Use 3.14 for p. 85.3p ft3, 267.8 ft3 36p m3, 113.0 m3 1936p in2, 6079.0 in2 3.r = 22 in 4.d = 1.5 mi 2.25p mi2, 7.1 mi2

  17. Lesson Quiz: Part 2 5.A basketball has a circumference of 29 in. To the nearest cubic inch, what is its volume? 412 in3

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