How do you convert Cartesian coordinates to polar

(x,y) --> (r,theta)

r=sqrt(x^2+y^2) <-- absolute length

theta = arctan or inverse tan of (y/x)

e.g. (3,4) --> (r,theta)

r=sqrt(3^2+4^2)=sqrt(25)=5
theta=arctan(4/3)=53 degrees

so in polar coords, it is (5,53)

x = r*cos Θ
y = r*sin Θ
DA = dx dy = (r) dr dΘ