Cho hình chóp
, tứ giác
đáy là hình thang vuông tại
và
,
vuông góc với mặt phẳng
. Biết
. Mệnh đề nào sau đây sai?
![img1](https://cungthi.online/upload/questionbank3/eduquestion/2018451049568457920/obj2018451049568457920284423_images/obj2018451049568457920284423_img1.png)
![img2](https://cungthi.online/upload/questionbank3/eduquestion/2018451049568457920/obj2018451049568457920284423_images/obj2018451049568457920284423_img2.png)
![img3](https://cungthi.online/upload/questionbank3/eduquestion/2018451049568457920/obj2018451049568457920284423_images/obj2018451049568457920284423_img3.png)
![img4](https://cungthi.online/upload/questionbank3/eduquestion/2018451049568457920/obj2018451049568457920284423_images/obj2018451049568457920284423_img4.png)
![img5](https://cungthi.online/upload/questionbank3/eduquestion/2018451049568457920/obj2018451049568457920284423_images/obj2018451049568457920284423_img5.png)
![img6](https://cungthi.online/upload/questionbank3/eduquestion/2018451049568457920/obj2018451049568457920284423_images/obj2018451049568457920284423_img6.png)
![img7](https://cungthi.online/upload/questionbank3/eduquestion/2018451049568457920/obj2018451049568457920284423_images/obj2018451049568457920284423_img7.png)
A.
.
B.
.
C.
.
D.
.
Đáp án và lời giải