Somewhat related: performing two reflections can perform arbitrary rotations and translations: - If the two lines we're reflecting across meet at a point, we'l

Somewhat related: performing two reflections can perform arbitrary rotations and translations: - If the two lines we're reflecting across meet at a point, we'll get a rotation around that point (with twice the angle between the lines) - If the two lines are parallel, we'll get a translation (perpendicular to the lines, of twice the distance between the lines) In projective geometry (where parallel lines "meet at infinity"), rotation and translation are the same thing. There's also a link to geometric algebra, which composes reflections into arbitrary "rotors"/"motors" (which are the same thing, projectively). To transform an object with a rotor, we apply it twice; due to this underlying 'two reflections' behaviour. (Demo: https://enkimute.github.io/ganja.js/examples/coffeeshop.html#pga2d_rotors_and_translators https://enkimute.github.io/ganja.js/examples/coffeeshop.html... )