Non-text problem 3*:
A point is randomly chosen in a disk of radius 1. Then the Cartesian coordinates (x, y) of this point have a joint pdf given by:
f(x, y) = { (1/π), x^2 + y^2 ≤ 1, (0 otherwise }
Let R = √(x^2 + y^2) be the distance from the point to the origin.
(a) For r in (-∞, ∞), find P(R ≤ r).
(b) Find the pdf of R.