Cho lăng trụ ABC.A’B’C’ có cạnh bên bằng 2a, đáy ABC là tam giác cân tại A;
. Hình chiếu vuông góc của A’ trên mp(ABC) trùng với trung điểm của cạnh BC. Tính thể tích khối chóp A.BB’C’C.
A.A:
![img1](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201744066539628245/obj201744066539628245413378_images/obj201744066539628245413378_img1.png)
B.B:
![img1](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201744066539628245/obj201744066539628245304870_images/obj201744066539628245304870_img1.png)
C.C:
![img1](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201744066539628245/obj201744066539628245620873_images/obj201744066539628245620873_img1.png)
D.D:
![img1](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201744066539628245/obj201744066539628245617937_images/obj201744066539628245617937_img1.png)
Đáp án và lời giải
Đáp án:C
Lời giải:
Đáp án C
Gọi H là trung điểm BC
cân tại A có góc
nên góc
![img1](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201744066539628245/obj201744066539628245410513_images/obj201744066539628245410513_img1.png)
![img2](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201744066539628245/obj201744066539628245410513_images/obj201744066539628245410513_img2.png)
![img3](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201744066539628245/obj201744066539628245410513_images/obj201744066539628245410513_img3.png)
![img4](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201744066539628245/obj201744066539628245410513_images/obj201744066539628245410513_img4.png)
![img5](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201744066539628245/obj201744066539628245410513_images/obj201744066539628245410513_img5.png)
![img6](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201744066539628245/obj201744066539628245410513_images/obj201744066539628245410513_img6.png)
![img7](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201744066539628245/obj201744066539628245410513_images/obj201744066539628245410513_img7.png)
![img8](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201744066539628245/obj201744066539628245410513_images/obj201744066539628245410513_img8.png)
![img9](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201744066539628245/obj201744066539628245410513_images/obj201744066539628245410513_img9.png)
![img10](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201744066539628245/obj201744066539628245410513_images/obj201744066539628245410513_img10.png)