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2 cuts and then get 5 triangles


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#1 Benson

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Posted 27 September 2007 - 03:25 AM

How to use a scissors to cut any 1 rectangle shape of paper 2 times and get no more or less 5 triangles?
Spoiler for solution

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#2 bonanova

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Posted 28 September 2007 - 06:35 AM

Do the cuts have to be straight lines?
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#3 Benson

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Posted 28 September 2007 - 06:36 AM

Do the cuts have to be straight lines?


Yes.
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#4 bonanova

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Posted 28 September 2007 - 07:28 AM

For the cut-pieces of a rectangle to form triangles, the cuts must pass thru corners [not sides].
Only two such cuts exist - along the two diagonals.
That gives you 4 triangles, not 5.

The only other way to cut a rectangle is to cut it after it has been folded.

All my tries at this so far have led to an even number of triangles.
I'll keep trying.
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The greatest challenge to any thinker is stating the problem in a way that will allow a solution.
- Bertrand Russell

#5 Benson

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Posted 28 September 2007 - 08:45 AM

For the cut-pieces of a rectangle to form triangles, the cuts must pass thru corners [not sides].
Only two such cuts exist - along the two diagonals.
That gives you 4 triangles, not 5.

The only other way to cut a rectangle is to cut it after it has been folded.


that's the trap. :)
Spoiler for hint

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