6. A dart is equally likely to land at any point (X, X3) inside a circular target of unit radius. Let R and be the radius and angle of the point (X, X3). (a) Find the joint cdf of R and . (b) Find the marginal cdf of R and . () Use the joint cdf to find the probability that the point is in the first quadrant of the real plane and that the radius is greater than 0.5. (d) Find the joint pdf of R and . (e) Find the marginal pdf of R and of . (f) Are R and independent