https://www.vtomb.com/video/N_tC79qqqic/maths-short-tricks-height-and-distance-%E0%A4%8A-%E0%A4%9A-%E0%A4%88-%E0%A4%A4%E0%A4%A5-%E0%A4%A6-%E0%A4%B0-part-2-video