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# How to determine if a point is on the left or right of a given line

Posted on 2008-10-31
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Hello,
This is a math / geometry question really.

I am trying to find out if a given coordinate (x0,y0) is on the left or right of a line formed by two other points (x1,y1) and (x2, y2).

I am sure its simple geometry, but if you don't know it, its not so simple :).
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Question by:HRCIII
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Accepted Solution

sdstuber earned 500 total points
ID: 22852095
determine  x =   (y0-y1)(x2-x1)/(y2-y1) + x1

if x < x0 then point is right of line
if x= x0 then point is on line
if x > x0 then point is left of line
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Author Closing Comment

ID: 31512130
Thank you,

This works beautifully and saves me a major amount of time.

-HRC
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Expert Comment

ID: 22852439
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