Dimensioning

Kayaker,

Couple ways to do that.

One way is to select the first two points in the direction parallel to the top chord (top and bottom of rafter) and then select the third point where you want the dimension to. You will then have to delete the one unnecessary dimension. You could also right click on the 9'-8 1/2" dimension and select "Insert Dim"

Another way would be to create a point perpendicular to the 2nd point on the top of the top cord line so that it is parallel with the first point.
When I do this I create a layer called points and create the point on that layer, then after dimensioning, I turn off the "points" layer so it doesn't show on the prints, but is there for verify your dimensions later should you need it.

I do more or less that same as Jim Rogers. I draw a line from the 2nd to perpendicular on the top line, and then I can make such measurements. But to put such lines on a seperate layer, was a quite good idea, because I normally delete such help line when the drawing is finished.