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anonymous

  • 5 years ago

Volume= 18 cm3 Height of the pyramid= 3 cm B1= 2 cm B2= 3 cm What is the height of the base?

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  1. anonymous
    • 5 years ago
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    you mean area of the base?

  2. anonymous
    • 5 years ago
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    wait, no. base area is .5xh(b1+b2) so i need the height

  3. anonymous
    • 5 years ago
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    i though height was given as 3 cm?

  4. anonymous
    • 5 years ago
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    thats the height of the pyramid

  5. anonymous
    • 5 years ago
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    okay, and what do you need to evaluate?

  6. anonymous
    • 5 years ago
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    the height of the base

  7. anonymous
    • 5 years ago
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    http://en.wikipedia.org/wiki/Pyramid_(geometry) are you talking about that? how is there a height of the base?

  8. anonymous
    • 5 years ago
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    x=18cm3

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  9. anonymous
    • 5 years ago
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    ah, so you should say its a trapezoidal pyramid.

  10. anonymous
    • 5 years ago
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    yes

  11. anonymous
    • 5 years ago
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    okay, do you know the formula to the volume of a pyramid?

  12. anonymous
    • 5 years ago
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    yes. 1/3 x B x H

  13. anonymous
    • 5 years ago
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    what is B in the formula?

  14. anonymous
    • 5 years ago
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    i dont know. b1 = 2 cm b2= 3 cm

  15. anonymous
    • 5 years ago
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    yess.

  16. anonymous
    • 5 years ago
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    okay you must always know what the letters mean in a formula. for example the area of a rectangle is the its length multiplied by its width. you shouldn't remember it as l x b, because when I ask you what l and b are, you don't have an answer to that.

  17. anonymous
    • 5 years ago
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    volume of a pyramid is one-thirds the product of the base area and its height

  18. anonymous
    • 5 years ago
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    yea

  19. anonymous
    • 5 years ago
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    so B is the area of the base. right, so substitute H and V in the equation

  20. anonymous
    • 5 years ago
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    right

  21. anonymous
    • 5 years ago
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    soooo,,,,,,,,,,,,,,,,,,,,

  22. anonymous
    • 5 years ago
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    so, tell me what you got after substituting the values of V and H.

  23. anonymous
    • 5 years ago
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    V= 18cm H= 3cm. h= i dont know

  24. anonymous
    • 5 years ago
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    substitute V = 18, H =3 in V = 1/3 x B x H and find the value of B.

  25. anonymous
    • 5 years ago
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    but H is the height of the pyramid, i need the height of the base (h)

  26. anonymous
    • 5 years ago
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    Yes, volume of a pyramid is 1/3 x Base area x Height of the pyramid. so once you find the base area of the pyramid, substitute its value as 1/2(b1+b2) x h and find h

  27. anonymous
    • 5 years ago
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    so how do you find h?

  28. anonymous
    • 5 years ago
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    I just told you. can you please just for the love of god substitute V and H in V = 1/3 B x H and give me an answer for B?

  29. anonymous
    • 5 years ago
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    BUT I DONT KNOW THE BASE. sorry i'm not good at math, my lord.

  30. anonymous
    • 5 years ago
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    what is so hard about this? 18 = 1/3 x B x 3 B =18 but we know that B = 1/2(b1+b2) x h so 18 = 1/2(2+3) x h h = 36/5

  31. anonymous
    • 5 years ago
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    you just have to work backward to get the base. you won't always find equations in the correct order. you must know how to manipulate equations to get your variable.

  32. anonymous
    • 5 years ago
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    where did we get 36

  33. anonymous
    • 5 years ago
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    multiply 18 by 2 and divide by 5.

  34. anonymous
    • 5 years ago
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    i got h = 7.2. is this correct?

  35. anonymous
    • 5 years ago
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    yeah. oooo you used a calculator to find the value of 36/5! good on you!

  36. anonymous
    • 5 years ago
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    btw, which grade are you in?

  37. anonymous
    • 5 years ago
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    7th

  38. anonymous
    • 5 years ago
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    okay. Have you ever done manipulation of equations?

  39. anonymous
    • 5 years ago
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    no

  40. anonymous
    • 5 years ago
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    like if x = y+2, what is y?

  41. anonymous
    • 5 years ago
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    x-2?

  42. anonymous
    • 5 years ago
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    then why do you say you haven't done any algebraic manipulation before?

  43. anonymous
    • 5 years ago
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    btw, h= 2.4. 1/2 x 2.4 (3+2) = 6. 6x3=18.

  44. anonymous
    • 5 years ago
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    why do you say 6 x 3 = 18?

  45. anonymous
    • 5 years ago
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    is the formula for volume of a pyramid area of base x height?

  46. anonymous
    • 5 years ago
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    because the height of the pyramid is 3 cm, so to find the volume you have to multiply the base by the height.

  47. anonymous
    • 5 years ago
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    oh yeah, divide by 3. nevermind...

  48. anonymous
    • 5 years ago
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    good, at least you figured that out on your own.

  49. anonymous
    • 5 years ago
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    oh stopp

  50. anonymous
    • 5 years ago
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    :D

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