Параллелограммы abcd и abpq находятся на разных плоскостях. докажите, что прямоугольник cdqp является параллелограммом​

 Сечение сферы представляет собой окружность.
На рисунке показано сечение шара,  8/проходящее через диаметр АВ и центр окружности сечения с диаметром ВС. ∠ВАС=45°.
КМ - касательная к окружности в точке В. АВ⊥КМ ⇒ ∠СВМ=45°.
∠СВМ - вырожденный случай вписанного угла, опирающегося на хорду ВС, значит ∠СВМ=∠ВОС/2 ⇒ α=90°.
Формула хорды: l=2R·sin(α/2)=D·sin(α/2).
ВС=8sin45=4√2.
Линия пересечения плоскостью - это длина окружности с диаметром ВС.
С=πD=BC·π=4√2π - это ответ.
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Это был общий вид решения задачи для любого угла α, но в данном случае можно проще.
∠α=90°, ∠ОВС=45°, значит ОВ=ОС ⇒ ВС=ОВ√2=4√2.

Speaking Task 1. Choose the question from the card on the topic Entertainment and fedia^ prime prime and be ready to answer it after the teacher starts the conversation. Produce a speech by giving extended answers to the questions. Share your ideas with the class. Teacher organizes a Socratic seminar, which helps him/her to assess learners while they are speaking on the toplic Entertainment and Media and he/she prepares and cuts down questions and expressions beforehand. Learners sit in a circle and answer the question using in their speech some formal and Informal expressions to present logically connected information to their classmates. Expressions: Stating an opinion The way I see it... Sorry to interrupt, but... Is it okay if I jump in for a second? Can I add something here? Can I throw my two cents in? Not necessarily Interrupting If I might add something..... I beg to differ No, I'm not so sure about that That's for sure Expressing disagreement I'd say the exact opposite I have to side with somebody (name)on this one I was just going to say that In my opinion Expressing agreement If you ask me.. That's exactly how I feel As far as I'm concerned. If you want my honest opinion..... You have a point there That's not always the case​