Trouble with some vector problems

[ramin86]

A vector is given by R = 1.50 i + 2.50 j + 2.89 k

Find the angle between R and the x, y, and z axis.

How would I do this?

[arildno]

1. What, in general, gives the angle between two vectors?
2. Which vectors might you use to represent the axes?

[ramin86]

Well I tried tangent of y/x, and got the angle, but it turned out to be wrong

[arildno]

Have you heard of one of these products?
"dot product", "scalar product", "inner product"?
(It's different names on the same "thing")

[ramin86]

lol well i have heard of a scalar product, not the other two however.

[arildno]

They're other names for the scalar product.
Now:
How is the value of the scalar product between two vectors related to the angle between them?