Trong không gian Oxyz, cho điểm
. Điểm D trong mặt phẳng (Oyz) có cao độ âm sao cho thể tích của khối tứ diện ABCD bằng 2 và khoảng cách từ D đến mặt phẳng (Oxy) bằng 1 có thể là:
A.A:
![img1](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201716077497179608/obj201716077497179608944196_images/obj201716077497179608944196_img1.png)
B.B:
![img1](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201716077497179608/obj201716077497179608371310_images/obj201716077497179608371310_img1.png)
C.C:
![img1](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201716077497179608/obj201716077497179608117362_images/obj201716077497179608117362_img1.png)
D.D:
![img1](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201716077497179608/obj201716077497179608433365_images/obj201716077497179608433365_img1.png)
Đáp án và lời giải
Đáp án:A
Lời giải:Do
với
Theo giả thiết:
Ta có
Suy ra
Cũng theo giả thiết, ta có:
Đối chiếu các đáp án chỉ có D thỏa mãn.
![img1](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201716077497179608/obj201716077497179608969388_images/obj201716077497179608969388_img1.png)
![img2](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201716077497179608/obj201716077497179608969388_images/obj201716077497179608969388_img2.png)
![img3](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201716077497179608/obj201716077497179608969388_images/obj201716077497179608969388_img3.png)
![img4](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201716077497179608/obj201716077497179608969388_images/obj201716077497179608969388_img4.png)
![img5](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201716077497179608/obj201716077497179608969388_images/obj201716077497179608969388_img5.png)
![img6](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201716077497179608/obj201716077497179608969388_images/obj201716077497179608969388_img6.png)