Area under Curve/Examples/sin x from 0 to pi

Example of Use of Area under Curve
The area bounded by the curve $y = \sin x$ and the $x$-axis between $x = 0$ and $x = \pi$ is $2$.

Proof
Let $\AA$ be the area in question.


 * Area-under-Curve-sin x.png

From Area under Curve we need to evaluate the definite integral:
 * $\AA = \ds \int_0^\pi \sin x \rd x$

So: