Checking if 3 points are collinear?

Posted on 2008-10-20
Last Modified: 2013-11-25

How can I check if 3 points are collinear?

Question by:DJ_AM_Juicebox
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LVL 84

Accepted Solution

ozo earned 250 total points
ID: 22762668

Assisted Solution

Talmash earned 250 total points
ID: 22784672
in case you are interested with 2D lines, OZO's answer is fine.

in case you want a 3D (streometric),

and you have 3 points A,B,C with coordinations (Xa,Ya,Za,..,Xc,Yc,Zc)

check if X,Y for all 3 points are linear.
check if X,Z for all 3 points are linear. (use Z coordinations as Y)
check if Y,Z for all 3 point are linear. (use Z coordinations as X)

LVL 84

Expert Comment

ID: 22785275
area works in 3D too
the magnitude of the cross product of any two sides is proportional to area

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