Magnitude and angle counterclockwise from the + x direction

[bearbratz]

Homework Statement

Express your answer in part (a) in terms of magnitude and angle counterclockwise from the + x direction.
Vector = -25.3i-1.2j

Homework Equations

arctan(ady/adx)

The Attempt at a Solution

Arctan(-1.2/25.3)=2.72
This is wrong... but I have no idea how to fix it.

 

[technicolour1]

Since tan is a trig function that repeats every 90deg, some consideration must be put into the signs of x and y. Since x and y are both negative, 180deg must be added to the value calculated to obtain the correct value. Likewise, if y is negative and x is positive, 270deg must be added. If x is negative and y is positive, 90deg must be added. This is shown when looking at a plot of the tan function. To confirm this answer (182.72), plug it into tan and see if it gives you your y/x ratio.

 

[bearbratz]

Thank you very much that worked.