Cho tứ diện ABCD có \(AB = CD = a\). Gọi M và N lầ...
Câu hỏi: Cho tứ diện ABCD có \(AB = CD = a\). Gọi M và N lần lượt là trung điểm của AD và BC. Xác định độ dài đoạn thẳng MN để góc giữa hai đường thẳng AB và MN bằng \(30^\circ .\)![](data:image/png;base64,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)
A \(MN = \frac{a}{2}\)
B \(MN = \frac{{a\sqrt 3 }}{2}\)
C \(MN = \frac{{a\sqrt 3 }}{3}\)
D \(MN = \frac{a}{4}\)
Câu hỏi trên thuộc đề trắc nghiệm
Đề thi thử THPT QG môn Toán năm 2019 - Thầy Chí - Đề số 15