Problem 1382 (difficulty: 3/10)

Let \(\displaystyle \gamma\) be the semicircle which is the right part of the circle centered at \(\displaystyle 0\) with radius \(\displaystyle a\) (i.e those points satsifying \(\displaystyle x\geq 0\)). \(\displaystyle \int_{\gamma} x\ \hbox{d}y=?\)

Give me another random problem!