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Can't figure this out (pic)
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Xeo
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Oct 20, 2004, 12:25 PM
 


I don't understand this. Using what I know of triangles, the hypotenuse is 13.93 units long. The area is 32.5 square units. But this picture makes it seem like the area can also be 31.5 square units. How is this so?
     
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Oct 20, 2004, 12:42 PM
 
If that was a piece of cheese, I would say a mouse ate it.
     
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Oct 20, 2004, 12:44 PM
 
The triangles aren't triangles. Look closely...they are slightly curved. This is especially visible on the top picture.
     
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Oct 20, 2004, 12:48 PM
 
Dang, beaten by Scifience!
     
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Oct 20, 2004, 01:16 PM
 
Photoshop draws a pretty straight line along the hypotenuse so I don't think it's because of any curve in the lines.

There is something interesting going on.
Areas (arbitrary units):
Red triangle=12
Green triangle=5
Orange = 7
Lt. Green = 8

The area for a triangle is basically an area for a rectangle divided by 2 (because if you inverted the triangle and lined the hypotenuses together you'd have a rectangle who's area you could calculate as lengthXwidth).

So the surface area for the top and bottom SHOULD be 32 if added up by the calculations above.

Well if you figure out the surface are for the top (5x13)/2=32.5 - a 1/2 square unit descrepancy.

The surface area for the bottom is (5x13)-2 [2 missing blocks]/2=31.5 - again a 1/2 square unit descrepancy but in the opposite direction.

The straight line distances from each apex jive if you want to get Pythagorean on me.

Still scratching my head about the surface area...
     
Addicted to MacNN
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Oct 20, 2004, 01:23 PM
 
here is another one for you-

http://www.funkypages.com/leprechaun/index.php

saw this this past weekend at the local sciencenter with the girlfriend. even with this solution it doesnt make any sense.

really cool to see in person... print it out if you're bored enough.

one arrangement (15 little buggers)-



the other (14 little buggers)-
     
Clinically Insane
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Oct 20, 2004, 01:30 PM
 
Originally posted by Scifience:
The triangles aren't triangles. Look closely...they are slightly curved. This is especially visible on the top picture.
Yes, that's it.

I recreated the first shape in in Excel

Then I copied and moved it to recreate shape 2, and and put a straight line on top of them.
You can clearly see where the difference comes from.



Click for bigger:
http://img.photobucket.com/albums/v4...ial/shapes.png

-t
     
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Oct 20, 2004, 01:51 PM
 
I stand corrected. The curve would definately be worth .5 square units...
     
Xeo  (op)
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Oct 20, 2004, 01:54 PM
 
Weird. Well thanks for the answer. I didn't see that at all. I still can't really see it on the ones I posted.
     
Clinically Insane
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Oct 20, 2004, 01:58 PM
 
Originally posted by Xeo:
I still can't really see it on the ones I posted.
No wonder.
Your picture has not been created like I did it, with 4 independent shapes and then moving them.

I guess your pictures have been drawn starting with the outlines of the big triangles first, and then subdivided into smaller shapes.
In that case, of course, their surface area doesn't match.

-t
     
   
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