Cho hình chóp đều S.ABCD có
, mặt bên (SBC) tạo với mặt đáy ( ABCD) một góc 450. Tính thể tích V của khối chóp S.ABCD .
A.A:
![img1](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201720088363431983/obj201720088363431983489979_images/obj201720088363431983489979_img1.png)
B.B:
![img1](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201720088363431983/obj201720088363431983852505_images/obj201720088363431983852505_img1.png)
C.C:
![img1](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201720088363431983/obj201720088363431983818577_images/obj201720088363431983818577_img1.png)
D.D:
![img1](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201720088363431983/obj201720088363431983784650_images/obj201720088363431983784650_img1.png)
Đáp án và lời giải
Đáp án:D
Lời giải:Đáp án D
Gọi M là trung điểm của BC, O là giao điểm của AC và BD
Ta có
Do AC=2a
Ta có:
![img1](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201720088363431983/obj201720088363431983323277_images/obj201720088363431983323277_img1.png)
![img2](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201720088363431983/obj201720088363431983323277_images/obj201720088363431983323277_img2.png)
![img3](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201720088363431983/obj201720088363431983323277_images/obj201720088363431983323277_img3.png)
![img4](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201720088363431983/obj201720088363431983323277_images/obj201720088363431983323277_img4.png)
![img5](https://cungthi.online/upload/questionbank3_20201220/eduquestion/201720088363431983/obj201720088363431983323277_images/obj201720088363431983323277_img5.png)