user-avatar
ngoxu714
2 năm trước
Cho hình chóp $S.ABCD$ có đáy $ABCD$ là nửa lục giác đều nội tiếp đường tròn đường kính $AD$, tâm $O$. Điểm $S$ nằm ngoài mặt phẳng $(ABCD)$ sao cho $\widehat{SDA}=\widehat{SOB}= 90^0$. Cho $I,F$ lần lượt là trung điểm $SA$ và $IA$. Tính khoảng cách giữa $2$ đường thẳng $DI$ và $BF$. Biết rằng $AD=2BC=4$ và góc giữa $(SAD)$ và đáy là $60^0$.
Thích Trả lời Chia sẻ

Các câu hỏi liên quan

IX. Read the following passage and fill in each gap with a suitable word by marking the letter A' B' C or D .(2 pts) The Earth has been getting warmer in the past 100 years. It (1).......global warming.(2). 1992° the warmest temperatures have been recorded on the Earth each year. Scientist tried to find out (3)...... the Earth was becoming warmer' (4)....they studied the oceans and the air to understand the reasons. They found out that human beings (5).........temperatures to go up. People have been burning fossil fuels (6)....petroleum 'coal and natural gas. As the world became (7)...........and the (8)........grew 'people burned more and more fossil fuels. This caused carbon dioxide levels to go up. The carbon dioxide also filled the air. It acted like a blanket (9....kept the Earth warmer' so the land 'air and oceans began to heat up (10)...... .... 1. A. calls B. is calling C. is called D. has called 2. A. For B. Since C. when D. In C. who C. but C. let C. as 3. A. what B. which D. why 4. A. so B. because D. however 5. A. made B. caused D. brought 6. A. like B. such D. alike 7. A. industrialize B. industrializes C. industrializing C. populate D. industrialized 8. A. popular B. population D. popularity 9. A. who B. what C. whom D. that 10. A. quick B. quickly C. fastly D. rapid

2018 © Loga - Không Ngừng Sáng Tạo - Bùng Cháy Đam Mê
Loga Team