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Bài 1: Cho hình hộp chữ nhật ABCD.A'B'C'D' có AB=AA'=a, AD=2a. Tính góc giữa đường chéo A'C và mặt phẳng đáy ABCD. Bài 2: Cho hình chóp S.ABCD có đáy ABCD là hình chữ nhật. M là trung điểm CD. Biết SA=SB=SC=SD=a căn 2 , đường tròn ngoại tiếp ABCD có bán kính bằng a. Gọi anpha là góc giữa SM và mặt đáy. Tính tan anpha ?
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