October 19th, 2008, 12:09 PM  #1 
Newbie Joined: Dec 2007 Posts: 8 Thanks: 0  Geometry problem
Here´s the problem: what is the lenght of de diagonal DH. See image>> Strangley by doing it wrong i get the correct answer! Hope someone can tell me more. Thanks, jonathan 
October 19th, 2008, 12:29 PM  #2 
Senior Member Joined: Jul 2008 Posts: 895 Thanks: 0  Re: Geometry problem
Think of a box bounded and defined by A, B, H, D and E. The rest is a red herring [there, and true, but extraneous.] DH is simply the body diagonal of that box: sqrt(4^2 + 2^2 + 3^2).

October 19th, 2008, 03:31 PM  #3 
Global Moderator Joined: Dec 2006 Posts: 20,966 Thanks: 2215 
I don't undertand your calculation of DG, as DG = 5 by Pythagoras's theorem. I don't understand why you say the angle G is not a right angle, as it is a right angle. 
October 20th, 2008, 03:17 AM  #4 
Newbie Joined: Dec 2007 Posts: 8 Thanks: 0  Re: Geometry problem
wow! Thanks guys ! I understand it now, it seems very simple, by just seeing a different shape inside the box! I was making it too dificult.

October 20th, 2008, 06:39 AM  #5 
Senior Member Joined: Jul 2008 Posts: 895 Thanks: 0  Re: Geometry problem
You might make it more interesting by finding angle HCD [which is not 90].

October 21st, 2008, 01:13 PM  #6 
Newbie Joined: Dec 2007 Posts: 8 Thanks: 0  Re: Geometry problem
hmm,, i will have to think about how to do that... sure you will now someway, or do i have to work on the problem? 
October 22nd, 2008, 12:33 AM  #7 
Global Moderator Joined: Dec 2006 Posts: 20,966 Thanks: 2215 
Finding that angle requires use of trigonometry as well as geometry.

October 22nd, 2008, 06:32 AM  #8  
Senior Member Joined: Jul 2008 Posts: 895 Thanks: 0  Re: Quote:
 
October 22nd, 2008, 09:23 AM  #9 
Newbie Joined: Dec 2007 Posts: 8 Thanks: 0  Re: Geometry problem
so there is more in mathematics than only logic... the use of imagination an intuition?

October 22nd, 2008, 03:57 PM  #10  
Senior Member Joined: Jul 2008 Posts: 895 Thanks: 0  Re: Geometry problem Quote:
 

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