coordinates

bobis · Post by **bobis** » Sun May 28, 2006 2:37 pm

I have 2 coordinates (-7, 8 ) and (-8, 7). how do I link the two with a solid line?

Post by **DPlotAdmin** » Sun May 28, 2006 3:27 pm

Use Edit>Edit Data to enter those values, or just copy the following and click the Paste button in DPlot:

-7,8
-8,7

If you don't initially see a line segment between those two points, select Options>Symbol/Line Styles.

bobis · Post by **bobis** » Sun May 28, 2006 6:14 pm

thanks a million!!!
you helped me 100% but I still have a problem.
I need to find the point where 2 lines meet and it doesent shoe after I evter them.

the points are -7,-8 and -4,11 then the second line is 0,3 and -4,-2

Post by **DPlotAdmin** » Sun May 28, 2006 8:00 pm

In general you'd use Info>Find Intersections to find the intersections of two curves. But since your 2 lines don't intersect and it is fairly obvious when looking at the graph that they don't intersect... well I'm not real sure what you're asking.

If you want to know where the projections of two lines with those same slopes intersect then you can do a curve fit (Generate>Polynomial Curve Fit) with order=1 on one or the other line, and when prompted for a start X and end X use values that overlap the extents of the other line. For example, do a curve fit on the 2nd curve. You'll get a dialog box giving you the equation of that line (y=3+1.25x). Click OK. In the "Lower limit" box enter -7, then click OK. Select Info>Find Intersections. Select "Curve #1" in the first list and "y=3+1.25x" in the second list. Check the "Insert new data..." and, if you want the intersection labelled, check "Add labels at intersections". You should then get an intersection at -6.557377,-5.196721.