Assuming
r > 0 and 0 ≤ θ < 2π,
the point p has polar coordinates
(r, θ) =

On a Cartesian plan & from the origin, draw a cercle &  a  radius(r)  that intersect  the cercle in P so that to form angle Ф, with the horizontal, then you will notice that the coordinate of P are rsinФ & rcosФ, which are the polar coordinate of P(rsinФ, rcosФ)

1/2 in. = 5 miles
1 in. / 2 = 1/2 in.
8 * 2 = 16
16 * 5 = 80 miles