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Geometry help please

Discussion in 'BBS Hangout' started by Ubiquitin, Jun 6, 2002.

  1. Ubiquitin

    Ubiquitin Member
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    :confused: Ok, I am stumped on this one...

    ABCD is a Trapeziod with bases 4cm and 12cm with diagonals AC and DB intersecting at O. Find the ratio of the areas of:
    a.triangle ABD and triangle ABC
    b.triangle AOD and triangle BOC
    c.triangle ABD and triangle ADC

    diagram:
    * 4cm
    **D__C
    **/ O\ O is about in the right pkace
    A/_______\B
    * 8cm
     
    #1 Ubiquitin, Jun 6, 2002
    Last edited: Jun 6, 2002
  2. Ubiquitin

    Ubiquitin Member
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    :confused: I think its a.1:1 b.1:1 c.3:1 but not sure
     
  3. Ollie

    Ollie Member

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    What is the correct length of AB, 8 or 12? Is <DAB the same as <CBA?
     
  4. hoopgod13

    hoopgod13 Member

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    going by what u wrote and not the diagram (which conflict)...i'll confirm ur answers. But better get a second opinion.
     
  5. Mango

    Mango Member

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  6. R0ckets03

    R0ckets03 Member

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    Free post fever gettin to ya? ;)
     
  7. FlyerFanatic

    FlyerFanatic YOU BOYS LIKE MEXICO!?! YEEEHAAWW
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    It cant be that can it? It wants the ratio of the whole triangles? not seperate, right? I have this trapezoid drawn out i am trying to figure it out. You have to cross multiply for ratios i believe. Thats all i can recall and that might not be right. I took Geomerty this year but i am not good at math.
     
  8. Mango

    Mango Member

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    No.......I did the trapezoid thing in text characters and it got completely changed after the BBS software finished with it.

    Just decided to delete instead of spending time trying to guess at how to beat the problem.


    Mango
     
  9. Kimble14

    Kimble14 Member

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    You're right, Azadre.

    Parts A and C are straightforward -- the area of a triangle is one-half its base times its height. Plug in the lengths of the bases, and you get something like 6h to 6h and 6h to 2h.

    Using part A's result will help you in part B:

    area of AOD = area of ABD - area of ABO = 6h - area of ABO
    area of BOC = area of ABC - area of ABO = 6h - area of ABO

    So, the ratio of the areas is 1:1. Q.E.D., or a little box, or w^5, or whatever you crazy kids use at the end of proofs these days. :)
     
  10. A-Train

    A-Train Member

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    You'll never become an engineer if you can't get a simple geometry question :)
     
  11. Ubiquitin

    Ubiquitin Member
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    :D I had the right answer in the end, but wasn't even 1% sure about it since that was the first time I've had to do a problem like that. Odd thing was the lesson that concerned area/proportions was two ahead of the assignment. Thanks guys...
     

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