Iranian Geometry Olympiad 2020 (Elementary) P1

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IftakharTausifFarhan
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Joined:Sat Dec 12, 2020 3:33 pm
Iranian Geometry Olympiad 2020 (Elementary) P1

Unread post by IftakharTausifFarhan » Sat Dec 12, 2020 4:54 pm

By a fold of a polygon-shaped paper, we mean drawing a segment on the paper and folding the paper along that. Suppose that a paper with the following figure is given. We cut the paper along the boundary of the shaded region to get a polygon-shaped paper.
Start with this shaded polygon and make a rectangle-shaped paper from it with at most $5$ number of folds. Describe your solution by introducing the folding lines and drawing the shape after each fold on your solution sheet.
(Note that the folding lines do not have to coincide with the grid lines of the shape.)
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Ahnaf_Akif
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Re: Iranian Geometry Olympiad 2020 (Elementary) P1

Unread post by Ahnaf_Akif » Thu Dec 31, 2020 1:00 pm

At first I will fold $AB$.Then,a part will go over $AE$.So I will fold $AC$ such that the part goes under $AE$.Next, I will fold $DE$ such that the upper part of $DE$ goes under $AE$.But a part will go under $BF$.So, I should fold such that the part stays between $BF$ and $AE$.For this, I will fold along $GH$.To make a rectangle I will fold along $EF$.
Here, $AE=BF$, $AB=EF$ and they are parallel.
So,$AEFB$ is a rectangle.
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