Cho hai vectơ
có
,
. Góc giữa hai vectơ
bằng bao nhiêu?
A.
![img1](https://cungthi.online/upload/questionbank3/eduquestion/20193901833810171805/obj20193901833810171805730701_images/obj20193901833810171805730701_img1.png)
B.
![img1](https://cungthi.online/upload/questionbank3/eduquestion/20193901833810171805/obj20193901833810171805476753_images/obj20193901833810171805476753_img1.png)
C.
![img1](https://cungthi.online/upload/questionbank3/eduquestion/20193901833810171805/obj20193901833810171805154880_images/obj20193901833810171805154880_img1.png)
D.
![img1](https://cungthi.online/upload/questionbank3/eduquestion/20193901833810171805/obj20193901833810171805219870_images/obj20193901833810171805219870_img1.png)
Đáp án và lời giải
Đáp án:A
Lời giải:
. Khi đó góc giữa hai vectơ
bằng
.
Vậy đáp án đúng là A.
![img1](https://cungthi.online/upload/questionbank3/eduquestion/20193901833810171805/obj20193901833810171805901333_images/obj20193901833810171805901333_img1.png)
![img2](https://cungthi.online/upload/questionbank3/eduquestion/20193901833810171805/obj20193901833810171805901333_images/obj20193901833810171805901333_img2.png)
![img3](https://cungthi.online/upload/questionbank3/eduquestion/20193901833810171805/obj20193901833810171805901333_images/obj20193901833810171805901333_img3.png)