polar equations problem

Question

Relation between Cartesian (x,y) and polar coordinates (φ,r) is given with x=rcosφ and y=rsinφ . Calculate φ(1,3) and r (1,3) .

Answer 1

It seems to mean convert to polar coordinates, so:

$$r(1,3)=\sqrt{1^2+3^2}=\sqrt{10}\;,\;\;\theta(1,3)=\arctan\frac31=71.565^\circ$$