When dealing with polar coordinates, it's easy to convert to rectangular coordinates


x = rcos(angle)

y=rsin(angle)

If the polar coordinate (r,angle) is (4, pi/2)

The rectangular coordinates are

x = 4cos(pi/2) = 0

y = 4sin(pi/2) = 4

If you are given rectangular coordinates, you can convert to polar coordinates


x^2 + y^2 = r^2

tan(y/x) = angle

So if you have the rectangular coordinates (2, 3)

The polar coordinates are

2^2 + 3^2 = r^2

13 = r^2

sqrt(13) = r

tan(3/2) = angle

angle = 56.3 degrees