The angle that A makes with the positive x axis

[Deading]

A=2i-10k

give the angle that A makes with the positive x-axis ?


do i need to make x axis=i and i go A.B/AxB ?

 

[Spinnor]

You have short sides of a triangle, you want the inverse tangent, see:

http://math12.vln.dreamhosters.com/wiki/Modeling_Real_World_Situations_Using_Trigonometric_Functions#Tangent_of_Theta

 

[tebes]

Is this 3-dimesional question?

 

[NascentOxygen]

Is this 3-dimesional question?

It is. But don't be put off, because it's actually an easy 3D question.