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   Sophie Schmieg (sophieschmieg@infosec.exchange)'s status on Monday, 29-Sep-2025 20:32:45 JST Sophie Schmieg

   Random childhood anecdote, posted as individual toot in order to not derail some random joke post about kids these days not being into non-Euclidean geometry:

   I have three siblings, spaced two years apart each. All four of us went to the same high school. My youngest sister's math teacher wanted to do a cute little segment about triangles always having inner angles sum up to 180 degrees. It was supposed to take the form of a trial. My sister was assigned the role of prosecutor charging a triangle accused of having an inner angle sum different from 180 degrees. Obviously, taking her role very seriously, she consulted the Schmieg dinner table, and a plan was hatched, involving a grapefruit and a marker. The trial came, and just as the defense had produced what they thought was irrefutable proof that their client was innocent, my sister took out the grapefruit, drew a triangle connecting one pole to the equator using three right angles, and said "So how do you explain this?!?" Leading to the teacher/judge having to explain non-Euclidean geometry to a bunch of 10 year olds.

   And to make this anecdote even better, in a different class the same day she had a substitute teacher who didn't know my sister, but seeing the triangled up grapefruit, approached her and asked her "Are you a Schmieg?". Our family name has racked up quite some reputation…

   • GreenSkyOverMe (Monika) repeated this.
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     Sophie Schmieg (sophieschmieg@infosec.exchange)'s status on Monday, 29-Sep-2025 20:33:18 JST Sophie Schmieg

     in reply to

     Nota Bene: since this story took place in Germany, the math teacher in question was quite well paid and had a university level mathematics education to fall back to, which, from having taught that course myself later, should include a full class on geometry, teaching not just the Euclidean, but the Hilbert axiomatisation. He also taught the math extracurricular, so he was very much up to the challenge 🙂.
     The triangle on the stand was still acquitted on account of being planar itself, so the story had a happy ending, and no triangles had to go to geometry jail.

   • Embed this notice
     Chip Unicorn (chip_unicorn@im-in.space)'s status on Monday, 29-Sep-2025 20:33:49 JST Chip Unicorn

     in reply to

     • Jens Finkhäuser
     • Alex@rtnVFRmedia Suffolk UK

     @vfrmedia @jens @sophieschmieg

     Try this out on the next grapefruit you see:

     Draw a circle around the equator of your grapefruit.

     Draw a line from the equator to the north pole of your grapefruit.

     Make a right angle at the north pole, then draw that line down to the equator. You will have a triangle covering 1/8 of the grapefruit.

     Every angle of the filled-in triangle is a right angle.

     Every right angle has 90 degrees, so that triangle has 270 degrees inside of it.

     (This works because it's on a sphere, not on a plane.)

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     Alex@rtnVFRmedia Suffolk UK (vfrmedia@social.tchncs.de)'s status on Monday, 29-Sep-2025 20:33:50 JST Alex@rtnVFRmedia Suffolk UK

     in reply to

     • Jens Finkhäuser

     @jens @sophieschmieg I had to look up a maths article on Wikipedia to understand the full story 😁

     I'm still not sure if I understand *all* of the article, but until today i'd never even thought about this concept..

     GreenSkyOverMe (Monika) repeated this.
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     Jens Finkhäuser (jens@social.finkhaeuser.de)'s status on Monday, 29-Sep-2025 20:33:52 JST Jens Finkhäuser

     in reply to

     @sophieschmieg That is cute!