Define gable roof by two exterior and one parallel interior wall?

[CaseyT]

I'm trying to create the roof / cathedral ceilings for an as-built of a rectangular house where the north and south exterior walls are 8' tall and 28' apart, and there is a parallel load bearing interior wall that is off-set from the mid line by 3.5' and is 9'-5" tall. There is no ridge beam, the rafters simply sit on this interior load bearing wall (and opposite pairs of rafters are off-set so they sit next to each other and are nailed together). The ceiling drywall is simply screwed to the underside of the rafters (which are 2x8s). I don't know the roof pitch, only the heights of the walls and the distance between them. Is there a way to get the roof planes (with the two different unknown pitches) to sit on both the exterior and the interior walls?

 

I thought maybe if I lock the ridge height I could pivot the roof plane down so that it set on the exterior walls, but I don't see a way to do that? Trying to lock to the baseline height results in a mismatched roof elevation at the ridge given the off-set. Is there a way to pivot the roof planes?

[glennw]

You don't even have to do the math to work it out.

Draw a simple section view with cad and let Chief do the math.

Your roof angles are 7.683982 and 4.628138