[Multivariable Calc]

Let R be the region that is inside of the cardioid r=2 + cos(theta) and outside the circle r=2?

So i need to calculate the:

*area of R, as well as

*the volume above R and below plane z=12-3x

*the density of that solid if the density d(x,y,z) =z

*the center of mass of that solid

Not asking for answers but how would I start these and when would I use polar coordinates if at all?