Finding the area under a speed time graph I recently learned about integration and I wondered how it could be applied to a speed time graph since it does not have a particular equation of a line that one can integrate. Do you split it into parts? I have heard of a type of integration which specialises in putting shapes under th graph to find the area so that might be the answer. An example of one can be something like this :

Thanks for the clarification 
Gedr
Edit : I'm mainly interested in points C to D since all others are basically triangles. 

This graph is a Position(time), it's antiderivative will give you the absement.
To calculate the area under this graph you can separate into these subregions:
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Then each area is just a simple geometric figure, for the rectangles you use the very well known formula $base\cdot height$ and for the triangles $ \dfrac {base\cdot height} 2$.
Notice, however, that to calculate the area under the curved region, we need the formula that describes the position in that timeframe.
E: I didn't see your edit, we can approximate that area without knowing the formula splitting that region into smaller rectangles, triangles, etc.
