1. The problem statement, all variables and given/known data I am trying to find the direction of an E-Field from a given E-Field vector in 3d space. If I have an electric field vector of (-1i, -2j, 3k), the magnitude of the field is sqrt(-1^2 + -2^2 + 3^2) = 3.74, but how do I find the direction? 2. Relevant equations tan(y/x)? 3. The attempt at a solution In 2d space I understand that the direction would be presented as an angle in relation to the positive x-axis. e.g. E-Field is 1000 N/C, 90 degrees counterclockwise from +x-axis. I am lost as to how this is both calculated and presented in 3 dimensions, however.