If you want to sound extra clever, here’s a mental shortcut I call the "Double and Subtract" trick. Take the midpoint and multiply each coordinate by 2. Then subtract the known endpoint’s coordinates from that double.
Using our example: midpoint (5, 7) doubled is (10, 14). Subtract the known endpoint (2, 3) and you get (8, 11). Same answer, less brain strain. It’s like baking a cake from a box mix—cheating, but who’s judging?
When Life Gives You Fractions (Don’t Cry)
Sometimes the coordinates or midpoints have fractions or decimals. Don’t let them scare you—just treat them like normal numbers. For instance, if your midpoint is (1.5, 0.75) and your known endpoint is (2, -1), double the midpoint: (3, 1.5). Subtract the endpoint: (3 - 2, 1.5 - (-1)) = (1, 2.5).
See? Fractions just want to be included in the party. They’re not mean—they’re just wholesome in a different way.
