Is -arctan(x/y) equal to arctan(y/x)?

[knowLittle]

Homework Statement

-arctan(x/y) = arctan(y/x) ?

Are they equivalent? I can't find anything online and I have seen that my solution to some problem involves
-arctan(x/y) and it agrees with Wolfram Alpha. On the other hand, my professor's solution shows the arctan(y/x) and this is why I am doubtful.

Any ideas?
Thank you.

 

[Dick]

Homework Statement

-arctan(x/y) = arctan(y/x) ?

Are they equivalent? I can't find anything online and I have seen that my solution to some problem involves
-arctan(x/y) and it agrees with Wolfram Alpha. On the other hand, my professor's solution shows the arctan(y/x) and this is why I am doubtful.

Any ideas?
Thank you.

They aren't equal. That would be silly, put x=1 and y=1. But the derivative d/dx with y a constant of arctan(y/x) is the same as the derivative of -arctan(x/y) if that's any help.