Сечением прямоугольного параллелепипеда ABCDA1B1C1D1{"color":"#202335","fontFamily":"stix","language":"ru"} плоскостью α{"color":"#202335","fontFamily":"stix","language":"ru"} содержащей прямую BD1{"color":"#202335","fontFamily":"stix","language":"ru"} и параллельной прямой AC{"color":"#202335","fontFamily":"stix","language":"ru"}, является ромб.
а) Докажите, что грань ABCD{"color":"#202335","fontFamily":"stix","language":"ru"} — квадрат.
б) Найдите угол между плоскостями α{"color":"#202335","fontFamily":"stix","language":"ru"} и BCC1{"color":"#202335","fontFamily":"stix","language":"ru"}, если AA1 = 16{"color":"#202335","fontFamily":"stix","language":"ru"}, AB = 6{"color":"#202335","fontFamily":"stix","language":"ru"}.
