Предмет: Геометрия, автор: KirilMefodi

Помогите решить задачу по геометрии!

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Автор ответа: orjabinina

Стереометрия .Определите вид параллелограмма АВСD

Объяснение:

Тк. КВ⊥( АВС) , то по т. о трех перпендикулярах : если наклонная КС⊥CD , прямой лежащей в плоскости , то и проекция ВС⊥CD.

Значит в параллелограмме ABCD , ∠BCD=90° ⇒∠BAC=90° , как противоположные. Тогда на углы ∠B=∠D=(360°-180°):2=90°.

Все углы параллелограмма прямые ⇒ABCD-прямоугольник.

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