cross-posted from: https://lemmy.ml/post/14733630
image description
Standard "they don't know" meme format, featuring line art of "That Feel Guy" wearing a party hat standing in a corner while other people are dancing. An image of an icosahedron formed by three mutually perpendicular golden ratio rectangles sits in front of That Feel Guy. The caption text says "They don't know that three mutually perpendicular golden ratio rectangles, with edges connecting their corners, form a regular icosahedron."https://en.wikipedia.org/w/index.php?title=Regular_icosahedron&oldid=1219666251#Construction
Almost. A 3 x 5 card does not use the golden ratio. If you cut two inches from the long side, you get a square that is 3 x 3 and a rectangle that is 2 x 3. 2/3 is not equal to 3/5.
The golden ratio occurs when a/b = (a+b)/a and it is also the ratio of the side of a pentagram to its diagonal. That's why this works.
It's still pretty close. 3(0.5(1+sqrt(5))) ≈ 4.854 ≈ 5, just barely over 3% higher.