Need Urgent help

[Kirix]

I'm currently learning vectors and i came across this website which test me on vectors. However, i am stuck on the 2nd question can you guys teach me? TYVM.
Btw is there any math discord or telegram group that i can join to ask questions?

 

[Dr.Peterson]

I'm currently learning vectors and i came across this website which test me on vectors. However, i am stuck on the 2nd question can you guys teach me?

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These questions are about applying properties of vectors, and in particular of the dot product. Do you have a list of those properties?

You got the second part right. The first requires you to notice that these are unit vectors. For the third, I think you just used the wrong two facts.