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Kailee1423

  • one year ago

I need help with a few questions that I got wrong on my homework. 1.Use formulas to find the lateral area and surface area of the given prism. Round your answer to the nearest whole number. (Pic in comments) 2.Find the volume of the square pyramid shown. Round to the nearest tenth if necessary. (Pic in comments)

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  1. Kailee1423
    • one year ago
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  2. Kailee1423
    • one year ago
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    3.Find the volume of the square pyramid shown. Round to the nearest tenth if necessary. 4.Find the volume of the given prism. Round to the nearest tenth if necessary.

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  3. Kailee1423
    • one year ago
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    @phi @mathway

  4. phi
    • one year ago
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    which one do you want to do?

  5. Kailee1423
    • one year ago
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    We can start on the first one if you don't mind:) I just don't understand them.

  6. phi
    • one year ago
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    Use formulas to find the lateral area and surface area of the given prism. Round your answer to the nearest whole number. lateral area is the "side area" , which is the area not including the "top or bottom" That is not very clear, but we we assume the top and bottom are the triangles and that means the "sides" are the 3 rectangles.

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  7. phi
    • one year ago
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    The first step to doing this is find the length and width of each side can you say what the length and width of the "bottom rectangle" is ?

  8. Kailee1423
    • one year ago
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    23 and 9

  9. phi
    • one year ago
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    and the area of a rectangle is length * width so the area of the bottom side is 23*9

  10. Kailee1423
    • one year ago
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    Which sides do you do this to?

  11. phi
    • one year ago
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    we are finding the area of the sides that are "rectangles" this is the bottom side of the prism |dw:1441657465989:dw|

  12. Kailee1423
    • one year ago
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    And the top would be 23*12.04?

  13. phi
    • one year ago
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    yes

  14. Kailee1423
    • one year ago
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    Do we need to do the back too? If we did then I think it would be 8*23

  15. phi
    • one year ago
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    yes. also the back. I am assuming the prism has "sides" and a "top and bottom" the top and bottom will be the two triangle faces (top and bottom should look alike) that leaves the 3 rectangles as the "sides" (even though the prism is laying on its side)

  16. Kailee1423
    • one year ago
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    Ok. Is there a reason why the rectangles couldn't be the top and bottom?

  17. phi
    • one year ago
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    It is "convention". (It is also sometimes not obvious) but in this case, with 3 sides, it is hard to argue 2 of them are the top and bottom (and the two triangle faces are sides). so just assume: we have more than two sides, and the sides all have the same shape. we have a top and bottom, and those two have the same shape.

  18. Kailee1423
    • one year ago
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    Ok that makes sense

  19. phi
    • one year ago
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    in this figure we have 3 rectangle faces and 2 triangle faces. so sides will be the rectangles and the 2 triangles will be the top and bottom.

  20. phi
    • one year ago
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    so the lateral area will be 207+276.92 + 184= 667.92 rounded to the nearest whole number: 668

  21. phi
    • one year ago
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    for the surface area (which is the lateral area plus the top and bottom) we need to add in the area of the two triangles can you figure the area of a triangle? height is 8, base is 9

  22. Kailee1423
    • one year ago
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    8*9 is 72 and if the other side is the same then the two together would be 144. Is that the surface area?

  23. phi
    • one year ago
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    the surface area is the total area. so add 72 to the lateral area to get the surface area

  24. Kailee1423
    • one year ago
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    Would I need to add 72 or 144?

  25. phi
    • one year ago
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    ** if the other side is the same *** yes, it is. You use the idea that opposite sides of a rectangle are equal thus |dw:1441658469941:dw|

  26. phi
    • one year ago
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    the area of a triangle is 1/2 base * height

  27. phi
    • one year ago
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    so you have 1/2 * 8 * 9 = 36 and the other triangle is the same 8 by 9 size so another 36 total of *both* triangles is 72

  28. Kailee1423
    • one year ago
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    Oh I left out the 1/2. I get it now

  29. phi
    • one year ago
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    surface area is 667.92 + 72 (notice we should always use the most accurate number) after we add up, then round to get the final answer.

  30. Kailee1423
    • one year ago
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    Would you like me to make a new question for the next one or do you want to just stay here?

  31. phi
    • one year ago
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    please make a new post. they get too long otherwise.

  32. Kailee1423
    • one year ago
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    Ok I'll tag you in it. Thank you so much!

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