Hi psygorn
Sorry about that.
I guess it has to do with the "display" nodes I used. ("NE" old version).
Wrong nodes have a red box on their upper left corner.
You can delete them or replace them with similar nodes.

Also I tried to make a more accurate pentagon. " pentagon_Quiz_Loop_Method.nod "
This time I used "loop" nodes. Give it a few seconds to see the pentagon !

So close! :)

Hi Elang,

I know as of now you have already solved the problem.

However, I think I might be able to correct your calculations a bit further.



Though I think it is a difficult problem for your nephew. But if he has more of these puzzles I would be happy to see them :-)

Remember alpha can have different values I chose the value that helps solving the problem.

The numerical method was done using a pocket calculator. So, maybe there are methods to calculate it with even more accuracy.

Do not take the last digit as granted. and for two alphas I think you can assume it is equal to 114.8120745 degrees.

If u use this amount then Angles A,B & E would all be equal to 114.8120745. However, even in this situation when u superzoom into it there u can see the corners are not on the big circle (which I think is not a calculating issue, it is rather displaying issue which I personally believe u can safely ignore it.)

And I failed to find a simple genius method to solve this problem, maybe there isn't such a solution. However, I cannot be sure!

- Psygorn

Hi Psygorn.

Thank you very much for the explanation. To be honest, I can only follow the first two lines from your picture. ^_^
However I've shared the picture to my nephew which amaze him quite a lot.

The original quiz was in Bahasa Indonesia which translation sounds like this:
"There are 3 lines. One line has length x√2 while the other has length x. Arrange the three of them into half pentagons so that all the ends are exactly on the circumference of a circle. Show me the picture. For bonus point: Mention the size of each corner formed and the radius of the intended circle."

The students has to solve this in their preference CAD application.

<<The students has to solve this in their preference CAD application.

So it's was a geometric solution asked and not a mathematical one! ;)

And it's really meant to be solved using constrains if we want to avoid calculations :
Here is a way to solve it using Freecad :

HI Pilou,

Indeed it is... Please forgive my English for misconceptions.

No problem! :) English is not my cup of tea too! :)

Hi Mip,

Thank you very much for pointing this up!
I'll let know my nephew about this FreeCAD.

Cheers!

Hi Elang,

Here is a short animation showing how to achieve it with Freecad's Sketcher Workbench.
(Grid snapping and Auto Constraints are deactivated)

I must add that, even if resolving this particular problem is very easy with Freecad's Sketcher Workbench,
I still highly prefer using MoI for every other concept or presentation drawings, 2D or 3D.
Freecad is interesting but not nearly as fast, intuitive and stable for Moments of Inspiration...
Even if it is Parametric, most of the time, I find it faster and simpler to redraw with MoI.

Hi VINC,

Thank you very much for pointing this up.

And, I completely agree with you and did tell my nephew that Moi is a great app which he confirmed. He even promote Moi to his colleagues and willing to give them basic tutorial for free.

Cheers!