Thursday, 21 January 2016

geometry - Five graded difficulty isosceles right triangle into square tilings


Similar to: Unlucky tiling: Arrange thirteen right isosceles triangles into a square


Two difficult "Seventeen right isosceles triangles into a square" tilings


V.hard problem, 20 right isosceles triangles into a square


Each tiling has only one solution, the smaller lists will be easier but all should be possible by hand, computers allowed.


The five challenges are to arrange $7, 13, 14, 15, 16$ right isosceles triangles of the listed areas into a square of area $882$ with no gaps or overlaps. The square has a diagonal of length $42$.


$7:$ $9, 18, 36, 72, 144, 162, 441$



$13:$ $16, 18, 25, 32, 36, 50, 64, 72, 81, 98, 100, 128, 162$


$14:$ $1, 2, 4, 8, 9, 16, 18, 25, 32, 36, 64, 98, 128, 441$


$15:$ $1, 2, 4, 8, 16, 25, 32, 36, 50, 64, 72, 98, 121, 128, 225$


$16:$ $1, 2, 4, 8, 16, 18, 25, 32, 49, 50, 64, 81, 98, 128, 144, 162$


The answer tick will be given to whomever posts the greatest number of "placed triangles" in completed puzzles first. In the unlikely event of a tie, the solver that got the highest scoring single puzzle wins.


By way of illustration/clarification, here are the right isosceles triangles of area


$1, 2, 4, 9, 16, 18, 50$


arranged into a $10\times 10$ square:


10x10_7



Answer




Here are the solutions to the five problems.



enter image description here
I was able to find by hand the first three solutions. The first one, in particular, can be downsized by a factor of 3 in all dimensions to simplify work. The last two I used PolySolver to help. The general methodology is to stack several triangles, often doubling in area, together.



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