Задача:
https://qa.studwork.ru/geometriya/880576-dan-kub-abcda1b1c1d1-rebro-kotorogo-ravno-1-sm-na-diagonali-s1v-ego-grani-otmetili-tochku-m-tak-chto-dmmc153?_ga=2.104642953.809555826.1636533434-793482486.1635849575