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Elise_a18

  • one year ago

Medal and Fan Not a multiple choice question, test, or Exam question What is the formula for finding the height of a square pyramid who's volume is 8 cubic feet and a base length of 2 ft?

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  1. Elise_a18
    • one year ago
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    @vera_ewing @Voltage @Vocaloid

  2. Vocaloid
    • one year ago
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    good, so we have V = (1/3)(r^2)(h) we have V and r, and we want to find h

  3. Elise_a18
    • one year ago
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    yep:)

  4. Vocaloid
    • one year ago
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    so we re-arrange our formula to get h = 3V/(r^2) now plug in V and r

  5. Elise_a18
    • one year ago
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    I'm having a heard time isolating h

  6. Vocaloid
    • one year ago
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    ok, want me to walk you through it?

  7. Elise_a18
    • one year ago
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    Oh! wait!

  8. Vocaloid
    • one year ago
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    nope, this formula works for a square pyramid a cone would be (1/3)(pi)r^2h

  9. Vocaloid
    • one year ago
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    if r = the side length of the base, that is

  10. Elise_a18
    • one year ago
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    Alright, let's start again. I have 2 formulas for a square pyramid \[\frac{ 1 }{ 6 } (b^3) \] and \[\frac{ 1 }{ 3 } (b) (h)\]

  11. Vocaloid
    • one year ago
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    hm... the first formula only works if the height is equal to the side length of the base

  12. Vocaloid
    • one year ago
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    lets use the second formula V = (1/3)bh where b is the area of the base and h is the height

  13. Elise_a18
    • one year ago
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    |dw:1444411817781:dw|

  14. Elise_a18
    • one year ago
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    Okay so the formula would be \[\frac{ 1 }{ 3 } (2) (h)\]

  15. Vocaloid
    • one year ago
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    oh, ok, if 2 is the area of the base, then yes

  16. Vocaloid
    • one year ago
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    V = (1/3)(2h) now multiply both sides by to "get rid of" the 1/3

  17. Elise_a18
    • one year ago
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    base length rather :P

  18. Elise_a18
    • one year ago
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    @Vocaloid

  19. Vocaloid
    • one year ago
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    wait, why "cubic feet"? that implies 3 dimensions

  20. Vocaloid
    • one year ago
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    if the side length is 2, then the base is 4

  21. Elise_a18
    • one year ago
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    yeah, it's a square pyramid. like in my drawing

  22. Elise_a18
    • one year ago
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    Ohh right! I forgot that BL= S^2

  23. Vocaloid
    • one year ago
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    right, so if b = 4 then V = (1/3)(4)(h) know how to isolate h now?

  24. Elise_a18
    • one year ago
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    Yeah I did it on my white board. Would it be h= \[\frac{ 1 }{ 3 } *8\frac{ 4 }\]

  25. Elise_a18
    • one year ago
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    oh. O-o

  26. Vocaloid
    • one year ago
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    nope, not quite

  27. Elise_a18
    • one year ago
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    |dw:1444412375012:dw|

  28. Vocaloid
    • one year ago
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    we want to "get rid of" the 1/3 fraction so we multiply both sides by 3

  29. Elise_a18
    • one year ago
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    not like this?

  30. Vocaloid
    • one year ago
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    V = (1/3)(4)(h) 3V = 4h with me so far?

  31. Elise_a18
    • one year ago
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    yes. So it would be V=8 right? because the vol is already given?

  32. Elise_a18
    • one year ago
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    OH! it's 6?

  33. Vocaloid
    • one year ago
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    nope, remember, we want to find h

  34. Vocaloid
    • one year ago
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    3V = 4h now divide both sides by 4

  35. Elise_a18
    • one year ago
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    i though we need to divide 3V by 4 to isolate h?

  36. Vocaloid
    • one year ago
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    right

  37. Vocaloid
    • one year ago
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    h = 6, right

  38. Vocaloid
    • one year ago
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    didn't see your answer up there ;P

  39. Elise_a18
    • one year ago
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    Yeay! Thank you so much! I know I'm kinda slow but I love it when I can actually understand X)

  40. Elise_a18
    • one year ago
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    i was seeing that V is substituted by 8

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