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Geometry
whether a point is to the right or left side of a line
http://stackoverflow.com/questions/1560492/how-to-tell-whether-a-point-is-to-the-right-or-left-side-of-a-line use of a cross product:
Where a = line point 1; b = line point 2; c = point to check against. If the formula is equal to 0, the points are colinear. If the line is horizontal, then this returns true if the point is above the line. |
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