Position of a point with respect to a line

Posted on 2013-12-04
Last Modified: 2013-12-04
Given a point (x,y)
and a line defined by (x1, y1) and (x2, y2)

what is the distance between the point and the line? and
what is the check whether the point lies within the end points?
All in terms of x's and y's for plugging in a computer program.
Question by:Saqib Husain, Syed
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Expert Comment

ID: 39696718
What does "within the end points" mean?
Is it a region bounded by lines through (x1, y1) and (x2, y2) perpendicular to the line between (x1, y1) and (x2, y2)?
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Author Comment

by:Saqib Husain, Syed
ID: 39696721
LVL 43

Author Comment

by:Saqib Husain, Syed
ID: 39696729
On a drawing, they are texts written next to lines at a defined distance.
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Expert Comment

ID: 39696730
There is a formula for the distance from a point to a line (not a line segment).

You would have to convert your line segment into the   ax + by + c = 0 form.
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Accepted Solution

ozo earned 500 total points
ID: 39696743
distance = |(x1-x)(y2-y)-(x2-x)(y1-y)|/sqrt((x1-x2)^2+(y1-y2)^2)

when ((x1-x2)*(x-x2)+(y1-y2)*(y-y2))/((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2)) is between 0 and 1, the point is within the end points
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Author Closing Comment

by:Saqib Husain, Syed
ID: 39697064
Great, thanks. Working perfectly.

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