Angle with respect to x or y axis.

[ysk1]

Could anyone please tell me what angle I need to find when the question asks to find an angle with respect to x axis. (or y axis)
Thank you.

 

[Mesmer]

with respect to the x or y: let's say that your angle is in 2-space or a 2-d angle. If you want to measure it with respect to the x-axis it means that you start on the x - axis and move counter clockwise to your angle. the same logic is used for the y as well

 

[ysk1]

Which side of x-axis (positive side or negative side) should I choose to start moving counter clockwise to my angle?

 

[Mesmer]

usually it is the positive side

 

[ysk1]

A question tells me to find an angle of a vector F with respect to positive x-axis.

Suppose the vector F points 17.1 degrees west of north. Then if I were to find angle of this vector with respect to positive x-axis, I add 17.1 degrees and 90 degrees and get 107.1 degrees, right?
On a question that asked to find the angle with respect to positive x-axis, I solved it as stated above, but it's wrong.
What is wrong with my method?

 

[Mesmer]

your angle is in the second quadrant. so you should do this 180-17.1 = 162.9 degrees.

 

[ysk1]

I tried 162.9 degrees but I was told it's wrong. It's very frustrating.. :(
The question should explain what it means by "with respect to positive x-axis".
What should I do?

 

[ysk1]

I still don't get this. Please tell me how to do this.

 

[ysk1]

Now I got it. I had made a small mistake.
Mesmer, thank you for your help. =)