Learning and geometry
Conventions in maths problem figures
Figures in maths problems: the marks carry the meaning — equal ticks, right-angle squares, parallel chevrons — and only the given values are written on the figure
This drawing comes from one YAML file. No shape was moved by hand.
Notes in the source (in Japanese)
問題の図は、数を並べる場所ではない。
何が等しいか・どこが直角か・どこが平行かを、線の引き方で先に渡す道具。斜線 1 本と 2 本は「別の組が等しい」こと。補助線は破線で引く ——元からある線と、自分が足した線を見て区別できるようにするため。
図は正確とは限らない。 読むのは数と印であって、目で測るものではない。
Source (YAML)
examples/gallery/219-算数数学の問題図.zumen.yaml
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Braille has only six dots, so “a” and “1” are the same shape until a number sign says otherwise
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Ruler-and-compass constructions: no scale is used, because equal compass openings make equal lengths
Two set squares come as a pair because two of them make ten angles in 15-degree steps, where one alone makes only four