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Grade 8 Surface area 1

Grade 8 Surface area 1. Surface area. The surface area of a solid figure is the sum of the areas of all faces of the figure.

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Grade 8 Surface area 1

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  1. Grade 8 Surface area 1 CONFIDENTIAL

  2. Surface area The surface area of a solid figure is the sum of the areas of all faces of the figure. An area of study closely related to solid geometry is nets of a solid. Imagine making cuts along some edges of a solid and opening it up to form a plane figure. The plane figure is called the net of the solid. The surface area of a rectangular solid is expressed in square units.

  3. In general, Surface Area of solid figures = 2 x area of the base +perimeter of the base x height If, B = area of the base P = perimeter of the base h = height SA = Surface Area Then, SA = 2B +Ph

  4. s s s s s s s s s Cubes A cube is a three-dimensional figure with all edges of the same length. If s is the length of one of its sides, then SA = 2(s2) + (4s)s = 6s2

  5. h w l Rectangular prism h w l SA = 2B + Ph SA = 2(lw) + (2l + 2w)h = 2(lw + lh + wh)

  6. Let us do some practice problems!

  7. 1) What is the surface area of the cubewith length of sides = 7 cm. • 296cm2 • 294cm2 • 394cm2 • 284cm2 b) 294cm2 CONFIDENTIAL 7

  8. 7cm 4 cm 5.5 cm 2) What is the surface area of the given rectangular prism. • 152cm2 • 177cm2 • 156cm2 • 158cm2 b) 177cm2 8 CONFIDENTIAL

  9. 7 4 8 3) What is the surface area of the given rectangular prism? • 266 cm2 • 258 cm2 • 232 cm2 • 368 cm2 c) 232 in2 9 CONFIDENTIAL

  10. 4) This net can be folded on the dashed lines to make a box. What is the surface area of the box? • 306 in2. • 370 in2. • 360 in2. • 350 in2. a) 306 in2 CONFIDENTIAL 10

  11. 5) Gina has a sheet of cardboard that measures 9 feet by 6 feet. She uses scissors and tape to make the entire sheet of cardboard into a closed box that is a perfect cube. What is the surface area of the box? • 81 feet2 • 63 feet2 • 45 feet2 • 54 feet2 d) 54 feet2 11 CONFIDENTIAL

  12. 6) How many unit cubes would it take to fill the box with an area of 10 square feet? • 4 cubes • 3 cubes • 2 cubes • 1 cube c) 2 cubes 12 CONFIDENTIAL

  13. 7) The rectangular prism at the right is made from centimeter cubes. What is the surface area of the prism? • 88 unit2 • 77 unit2 • 66 unit2 • 76 unit2 a) 88 unit2 CONFIDENTIAL 13

  14. 8) What is the total surface area of the box, including the bottom and the top? • 405 unit2 • 408 unit2 • 406 unit2 • 409 unit2 b) 408 unit2 14 CONFIDENTIAL

  15. 9) What isthe surface area of the given box? • 336 cm2 • 346 cm2 • 326 cm2 • 376 cm2 a) 336 cm2 15 CONFIDENTIAL

  16. 10) What isthe surface area of the given box? • 82 cm2 • 72 cm2 • 92 cm2 • 102 cm2 c) 96 cm2 16 CONFIDENTIAL

  17. Assessment

  18. 1) The surface area of a cube is 24 ft2. Find the length of each edge. • 4 ft • 3 ft • 2 ft • 1 ft c) 2 ft CONFIDENTIAL 18

  19. 2) What is the length of each edge of the box that is a perfect cube with area 54 units2? • 2 units • 3 units • 4 units • 5 units b) 3 units 19 CONFIDENTIAL

  20. 11 8 8 3) What is the surface areaof the given Regular square prism? • 470 unit2 • 480 unit2 • 490 unit2 • 580 unit2 b) 480 unit2 20 CONFIDENTIAL

  21. 4) Bill has a sheet of cardboard with an area of 10 square feet. He makes the entire sheet of cardboard into a closed rectangular box. The four sides of the box have the same area, and the two ends have the same area. The area of each of the four equal sides is twice the area of each end. What is the area of each face of Bill’s box? • 2 unit2; 1 unit2 • 3 unit2; 1.5 unit2 • 4 unit2; 2 unit2 • 5 unit2; 2.5 unit2 a) 2 unit2; 1 unit2 21 CONFIDENTIAL

  22. 5) What is the surface area of the given Regular square pyramid? • 180 unit2 • 150 unit2 • 146 unit2 • 136 unit2 d) 136 unit2 22 CONFIDENTIAL

  23. 6) What is the surface area of the given square pyramid? • 26 yd2 • 22 yd2 • 24 yd2 • 28 yd2 c) 24 yd2 23 CONFIDENTIAL

  24. 7) What is the surface area of the given square pyramid? • 64 in2 • 56 in2 • 45 in2 • 74 in2 a) 64 in2 24 CONFIDENTIAL

  25. 8) What isthe surface area of the given rectangular pyramid? • 226 ft2 • 256 ft2 • 246 ft2 • 236ft2 d) 236ft2 25 CONFIDENTIAL

  26. 9) What isthesurface area of the given rectangular pyramid? • 92 yd2 • 94 yd2 • 96 yd2 • 98 yd2 b) 94 yd2 26 CONFIDENTIAL

  27. 10) What isthesurface area of the given rectangular pyramid? • 592 cm2 • 564 cm2 • 594 cm2 • 565cm2 d) 594 cm2 27 CONFIDENTIAL

  28. You did a great job today!

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