Предмет: Геометрия, автор: anatasia12

Ребята, помогите, пожалуйста, очень надо. Срочно!!!!!!!

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Автор ответа: Аноним

1

Угол равен 60°, КN - средняя линия треугольника АСD, поэтому параллельна ВС, значит, угол между КN и AС равен углу между AC и ВС, но т.к. тетраэдр правильный, то и треугольник АВС правильный, значит, все углы в нем по 60°, в т.ч. и искомый.

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