Answer
$\frac{2\sqrt 2-1}{3}$
Work Step by Step
$\int\int_{D}xdA=\int_{0}^{\pi/2}\int_{1} ^{\sqrt 2} (rcos\theta)rdrd\theta$
$=\int_{0}^{\pi/2}(cos\theta)d\theta\int_{1} ^{\sqrt 2} r^{2}dr$
$=(sin\theta)_{0}^{\pi/2}[\frac{r^{3}}{3}]_{1} ^{\sqrt 2}$
$=(1)\frac{2\sqrt 2-1}{3}$
$=\frac{2\sqrt 2-1}{3}$
