Cho hình chóp
có đáy
là hình vuông cạnh
. Hai mặt bên
và
cùng vuông góc với mặt đáy. Biết góc giữa hai mặt phẳng
và
bằng
. Gọi
lần lượt là thể tích khối chóp
và
với
,
lần lượt là trung điểm của
và
. Tính độ dài đường cao của khối chóp
và tỉ số
.
![img1](https://cungthi.online/upload/questionbank3/eduquestion/20193429721212810913/obj20193429721212810913238899_images/obj20193429721212810913238899_img1.png)
![img2](https://cungthi.online/upload/questionbank3/eduquestion/20193429721212810913/obj20193429721212810913238899_images/obj20193429721212810913238899_img2.png)
![img3](https://cungthi.online/upload/questionbank3/eduquestion/20193429721212810913/obj20193429721212810913238899_images/obj20193429721212810913238899_img3.png)
![img4](https://cungthi.online/upload/questionbank3/eduquestion/20193429721212810913/obj20193429721212810913238899_images/obj20193429721212810913238899_img4.png)
![img5](https://cungthi.online/upload/questionbank3/eduquestion/20193429721212810913/obj20193429721212810913238899_images/obj20193429721212810913238899_img5.png)
![img6](https://cungthi.online/upload/questionbank3/eduquestion/20193429721212810913/obj20193429721212810913238899_images/obj20193429721212810913238899_img6.png)
![img7](https://cungthi.online/upload/questionbank3/eduquestion/20193429721212810913/obj20193429721212810913238899_images/obj20193429721212810913238899_img7.png)
![img8](https://cungthi.online/upload/questionbank3/eduquestion/20193429721212810913/obj20193429721212810913238899_images/obj20193429721212810913238899_img8.png)
![img9](https://cungthi.online/upload/questionbank3/eduquestion/20193429721212810913/obj20193429721212810913238899_images/obj20193429721212810913238899_img9.png)
![img10](https://cungthi.online/upload/questionbank3/eduquestion/20193429721212810913/obj20193429721212810913238899_images/obj20193429721212810913238899_img10.png)
![img11](https://cungthi.online/upload/questionbank3/eduquestion/20193429721212810913/obj20193429721212810913238899_images/obj20193429721212810913238899_img11.png)
![img12](https://cungthi.online/upload/questionbank3/eduquestion/20193429721212810913/obj20193429721212810913238899_images/obj20193429721212810913238899_img12.png)
![img13](https://cungthi.online/upload/questionbank3/eduquestion/20193429721212810913/obj20193429721212810913238899_images/obj20193429721212810913238899_img13.png)
![img14](https://cungthi.online/upload/questionbank3/eduquestion/20193429721212810913/obj20193429721212810913238899_images/obj20193429721212810913238899_img14.png)
![img15](https://cungthi.online/upload/questionbank3/eduquestion/20193429721212810913/obj20193429721212810913238899_images/obj20193429721212810913238899_img15.png)
![img16](https://cungthi.online/upload/questionbank3/eduquestion/20193429721212810913/obj20193429721212810913238899_images/obj20193429721212810913238899_img16.png)
![img17](https://cungthi.online/upload/questionbank3/eduquestion/20193429721212810913/obj20193429721212810913238899_images/obj20193429721212810913238899_img17.png)
A.
.
B.
.
C.
.
D.
.
Đáp án và lời giải
Đáp án:A
Lời giải:
Phân tích: Do và
cùng vuông góc với mặt đáy nên
. Ta có
. Dễ thấy góc giữa hai mặt phẳng
và
là
. Ta có tam giác
là tam giác vuông cân đỉnh
. Vậy
. Áp dụng công thức tỉ số thể tích có:
.
Vậy đáp án đúng là A.