Hi,

I have a straight line whose start and end points are known. (Pt1 and Pt2)...

Is it possible to calculate the coordinates of a point that is on on this straight line at a distance of 1000 from pt1 or pt2...

thanks

- February 19th 2008, 07:51 PMayrusCalculating coords of a point on a straight line at a distance from start point...
Hi,

I have a straight line whose start and end points are known. (Pt1 and Pt2)...

Is it possible to calculate the coordinates of a point that is on on this straight line at a distance of 1000 from pt1 or pt2...

thanks - February 19th 2008, 08:26 PMJhevon
- February 19th 2008, 09:25 PMayrus
Hi jhevon,

thank you for your comment...

I need to write a program what could calculate the values as described in the topic...

If I were to calculate,

Distance Formula: Dist ^2 = (y2-y1)^2 + (x2-x1)^2

and substituting y=mx+c in the above equation...

This looks little tedious programmatically; I am wondering if there are any alternate ways of solving the problem...

thanks - February 20th 2008, 10:17 AMPlato
Suppose that P(a,b) & Q(c,d) are the end points of the line segments.

Define .

Now define , equation of the line determined by P & Q.

Note that so that is the point 1000 units from P in the Q direction.

Whereas is the point 1000 units from P in the direction opposite of Q (that is P is between that point and Q).

If you need distances from Q then just change the definition of the line.