hello
i wonder how you can decide the angle when changing to polar coordinates?
i know this:
x=rcos(delta)
y=rsin(delta)
delta= arctan (x/y)
but i find it very difficult to know the value of delta

Question

hello 
i wonder how you can decide the angle when changing to polar coordinates? 
i know this:
x=rcos(delta)
y=rsin(delta)
delta= arctan (x/y)
but i find it very difficult to know the value of delta

freckles · Answer

can you give an example of where you have trouble at

freckles · Answer

|dw:1437432457639:dw|
arctan will output values for these quadrants where theta is between -pi/2 and pi/2

freckles · Answer

so to get the other quadrants we have to be a bit more clever but not too much more

freckles · Answer

|dw:1437432533105:dw|
that was a straight line so if you really meant to have the angle there 
you can adjust your theta by adding pi to it