Double integral in polar coordinates

Evaluate the integral by changing to polar coordinates. ∫∫[D] x dA. Where D is the region in the first quadrant that lies bewteen the circles x^2+y^2=4 and x^2+y^2=2x.

Please, explain how can you find the limit for "r" ..

first circle has center (0,0), radius = 2

second circle has center (1,0), radius = 1

I know that

but where is D !!

"BETWEEN TWO CIRCLES" << Omg, i cant figure it out =(

And this is not for my homework

Actually, we dont hae homeworks in our university =D