Hey, I have a question:

This problem states that X and Y are uniformly distributed on the unit disk. It goes on to ask me questions like what is the joint density of the RVec X,Y, which is $\displaystyle \mathbf{1}_D\cdot \frac{1}{\pi}$... but then it asks questions specific to the individual variables.

For example, I am asked what $\displaystyle \mathbf{E}X$ is. Now, X is obviously not uniformly distributed; neither is y (if we take X,Y to be the x and y coordinates respectively).

Then if R is the distance from the point to the centre, find $\displaystyle \mathbf{E}R$ and Var(R).

Any tips/hints? I'm stuck on this one.

Thanks in advance!