Who wants to do my Geometry homework??

Discussion in 'Community' started by realityisterror, Jan 6, 2005.

  1. realityisterror macrumors 65816

    realityisterror

    Joined:
    Aug 30, 2003
    Location:
    Snellville, GA
    #1
    i can't get this problem.. :D

    using this diagram, find the area of pentagon BNREC...
    [​IMG]

    i can get the area of triangle BEC easily... i just can't get the BNRE part because of that little bend in there...

    also, the drawing isn't quite to scale, but none of the sides touch a point unless they are obviously on it...

    thanks,
    reality
     
  2. wordmunger macrumors 603

    wordmunger

    Joined:
    Sep 3, 2003
    Location:
    North Carolina
    #2
    I think I got it. You can easily get the area of the rectangle abnz, where z is an imaginary new point on line segment be. z is exactly 3 units above f. the area of triangle bnz is 1/2 area abnz. Now imagine a point x on segment vr, which forms square zfrx. It's easy to find the area of triangle xrn, so your job is done.
     
  3. AppleMatt macrumors 68000

    AppleMatt

    Joined:
    Mar 17, 2003
    Location:
    UK
  4. realityisterror thread starter macrumors 65816

    realityisterror

    Joined:
    Aug 30, 2003
    Location:
    Snellville, GA
    #4
    only on MR people... only on MR...

    you are a god wordmunger... i didn't really care if i missed one question... if was just driving me crazy.. :p

    thanks again,
    reality
     
  5. noel4r macrumors 6502a

    Joined:
    Jul 17, 2002
    Location:
    Los Angeles
    #6
    i got 369, i grouped them by 4 triangles and 1 square got the area then added them up.
     
  6. Daveway macrumors 68040

    Daveway

    Joined:
    Jul 10, 2004
    Location:
    New Orleans / Lafayette, La
  7. themadchemist macrumors 68030

    themadchemist

    Joined:
    Jan 31, 2003
    Location:
    Chi Town
    #8
    The way I see you doing it is getting the area of everything outside of the desired area (besides the bec part, which you already have). That stuff is simple enough to figure out because of the lengths given on the side. When you subtract it all, you are left with the area of the weird shape for which you're looking.

    Of course, wm beat us all to the punch.
     
  8. hcuar macrumors 65816

    hcuar

    Joined:
    Jul 23, 2004
    Location:
    Dallas
    #9
    Pah... that's not Geometry homework... Where's your T column proofs? heh... :D Now that's Geometry homework.
     
  9. Daveman Deluxe macrumors 68000

    Daveman Deluxe

    Joined:
    Jun 17, 2003
    Location:
    Corvallis, Oregon
    #10
    I think I have an even easier way (that is, one that doesn't require the creation of new points).

    Take the area of triangle bce, which is 162 units square. Then you place he same imaginary point z (I guess it does take one imaginary point) and then find the area of triangle bnz, which is 121.5 units squared. Then find the area of trapezoid nrfz, which is 22.5 square units, then find the area of triangle rfe, which is 4.5 units square. The total area is 310.5.

    That said, I agree with hcuar.

    Edit: I just realized that themadchemist's solution is even more elegant than mine is.
     
  10. Onishenko macrumors newbie

    Onishenko

    Joined:
    Nov 30, 2004
    #11
    Agreed. I did it differently, using some of the method that wordmunger used. But came to the same conclusion.

    369. On the money.

    Edit: Agreed with post above. Madchemist's method is alot simpler. Wish I saw that. Probably spent hours in 8th grade meditating over these types of questions when I could have used this simpler method.
     
  11. scem0 macrumors 604

    scem0

    Joined:
    Jul 16, 2002
    Location:
    back in NYC!
    #12
    Thinking about those hurts my soul :p;).

    Geometry is something I want to leave far, far behind. Algebra II was a bunch of fun, though :).

    scem0
     
  12. oldpismo macrumors member

    Joined:
    Aug 12, 2003
    Location:
    UK
    #13
    same method different answers

    I used the same method as wordmunger, and came up with 373.5, as did MacNext

    We seem to be getting alot of different answers to a relatively simple question.

    Peter
     
  13. jasylonian macrumors regular

    Joined:
    Sep 25, 2003
    Location:
    sacramento
    #14
    373.5 looks right to me. 162+162+36+9+4.5.
     
  14. Daveman Deluxe macrumors 68000

    Daveman Deluxe

    Joined:
    Jun 17, 2003
    Location:
    Corvallis, Oregon
    #15
    Well, I realized after seeing this that I did my arithmetic wrong. It is 373.5 units square.

    Good thing I check my own tests, I suppose.
     
  15. Ajmbc macrumors regular

    Joined:
    Jan 29, 2003
    Location:
    Louisiana
    #16
    Heh, Geometry is not geometry without the legendary 2 column proofs :p

    -ajmbc
     

Share This Page