Answer:
The polar coordinates appear in the form (r, θ), where r is the the radius from the center and θ is the angle. To get the radius, do the following.
[tex]r = \sqrt{x^2 + y^2} = \sqrt{1^2 + (-1)^2} = \sqrt{2}\\[/tex]
You can get the angle visually by drawing a point (1, -1) on a graph and seeing that it is 45 degrees from the top right quadrant (you can tell its 45 because both x and y have the same magnitude). Since there are 360 degrees, 360 - 45 = 315.
If you would like to find it mathematically, this is the way to do it
[tex]\theta = atan(y/x) = -45[/tex]
Notice that -45 degrees is just 360 - 45 = 315
Your answer would be
[tex](\sqrt{2}, 315)[/tex]