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#1 2006-04-20 02:11:02

jjones
Guest

points

i posted a while ago finding points on a line as i need to calculate if a given (X,Y) is on a line that spans from (x1,y1) to (x2,y2) i have the following

0= (y2-y1)/(x2-x1)X+ (y1-[(y2-y1)/(x2-x1)]*x1) -Y

but it only seems to work for horizontal lines my maths is pretty bad and i would really appreciate it if any one could explain  or even better tell me how i could make it work as i am really lost.

#2 2006-04-20 02:35:31

Jai Ganesh
Administrator
Registered: 2005-06-28
Posts: 45,956

Re: points

The equation of the line joining the points


is given by

Now, after forming the equation of the line joining the two points,
substitute the values (x,y) and see if the equation is satisfied. If yes, the point lies on the straight line, if no, it doesn't.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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