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hcuc1976
2 năm trước
cho hình chóp S.ABCD có đáy ABCD là hình thang đáy lớn là AD và AD=2BC, AC giao với BD tại o. Gọi M là trung điểm với SD, G là trọng tâm tam giác SCD. a. xác định giao tuyến của mặt phẳng (BOG) và mặt phẳng (SBC) b. chứng minh OG song song với mặt phẳng (SBC) c. Xác định thiết diện của hình chóp với mặt phẳng |(BCG). thiết diện hình là gì? Mình cảm ơn ạ :3
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