
Source: https://xkcd.com/2689/
Source: https://xkcd.com/2689/
For more details on how this rounding works, see https://www.explainxkcd.com/wiki/index.php/2585:_Rounding.
Source: https://xkcd.com/2526/
Source: https://xkcd.com/2545/
Source: https://xkcd.com/2533/
Geometry textbooks always try to trick you by adding decorative stripes and dotted lines.
If you’re having trouble getting the formulas behind the joke, please see https://www.explainxkcd.com/wiki/index.php/2509:_Useful_Geometry_Formulas.
Source: https://xkcd.com/2343/