Cho hình chóp
có đáy
là hình vuông cạnh
và cạnh bên
vuông góc với mặt đáy. Gọi
là trung điểm của cạnh
. Biết khoảng cách từ
đến mặt phẳng
bằng
, tính thể tích khối chóp
theo
.
![img1](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201715088436223905/obj201715088436223905319887_images/obj201715088436223905319887_img1.png)
![img2](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201715088436223905/obj201715088436223905319887_images/obj201715088436223905319887_img2.png)
![img3](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201715088436223905/obj201715088436223905319887_images/obj201715088436223905319887_img3.png)
![img4](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201715088436223905/obj201715088436223905319887_images/obj201715088436223905319887_img4.png)
![img5](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201715088436223905/obj201715088436223905319887_images/obj201715088436223905319887_img5.png)
![img6](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201715088436223905/obj201715088436223905319887_images/obj201715088436223905319887_img6.png)
![img7](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201715088436223905/obj201715088436223905319887_images/obj201715088436223905319887_img7.png)
![img8](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201715088436223905/obj201715088436223905319887_images/obj201715088436223905319887_img8.png)
![img9](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201715088436223905/obj201715088436223905319887_images/obj201715088436223905319887_img9.png)
![img10](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201715088436223905/obj201715088436223905319887_images/obj201715088436223905319887_img10.png)
![img11](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201715088436223905/obj201715088436223905319887_images/obj201715088436223905319887_img11.png)
A.
B.
C.
D.
Đáp án và lời giải
Đáp án:B
Lời giải:
Kẻ ,
nên:
Mà
Nên:
Do đó: .
Vậy đáp án đúng là: B.