Chapter 5.2, Problem 76E

In the following exercises, evaluate the double integral ${\displaystyle \underset{D}{\iint }f\left(x,y\right)dA}$over the region D.
76. $f\left(x,y\right)=2$ and $D=\left\{\left(x,y\right)|1\le y\le 1,y^2-1\le x\le \arccos y\right\}$