Well, for (5,0) the Polar Coordinates (r,theta) would be r = \sqrt{(5^2)+0^2} = 5
then the theta value would be Tan^{-1}(0)
or (-5,0) the Polar Coordinates (r,theta) would be r = \sqrt{(-5^2)+0^2} = 5
then the theta value would be Tan^{-1}(0)
for (0,5) the Polar Coordinates (r,theta) would be...