# Cumulative area

The plot on the left is the graph of
$$f(x) = \begin{cases}\dfrac{\sin(x)}{x},& \text{if } x \ne 0 \\ 1,&\text{if } x = 0.\end{cases}$$
Moving the red dot on the left along the x-axis with the mouse pointer displays the cumulative area
under the graph. At the same time, the plot on the right displays
the graph of the cumulative area, that is, the graph of
$$F(x) = \int_0^x \frac{\sin(t)}{t} dt,$$
where x is the current position of the red dot. In other words, the height of the sky blue
line on the right is equal to the area of the sky blue region on the left.

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