Alternate/ easy to follow solution:
Change of coordinates as $(x-1)=r\cos{\theta}$ and $y=r\sin{\theta}$
Then compute the following integral: $$\iint \frac{1}{2}(x^2+y^2)dA$$ $$=\int^{2\pi}_{0}\int^{1}_{0}(r^2+2r\cos{\theta+1)}dr\cdot d\theta$$ $$=\frac{3{\pi}}{4}$$
Alternate/ easy to follow solution:
Change of coordinates as $(x-1)=r\cos{\theta}$ and $y=r\sin{\theta}$ as the centre of the circle is xy-plane is offset to $(1,0)$
Then compute the following integral: $$\iint \frac{1}{2}(x^2+y^2)dA$$ $$=\int^{2\pi}_{0}\int^{1}_{0}(r^2+2r\cos{\theta+1)}dr\cdot d\theta$$ $$=\frac{3{\pi}}{4}$$