Out of square

[leekenning]

Hello!  Hoping someone can shed some light on this issue I can't figure out.  I'm essentially modelling a skewed cuboid that has a couple of other angled faces (one of them is sloped on two axis) but however I model it, a couple of the [supposed to be] 90 degree angles are out of square.

I tried drawing perpendicular sketches and experience the same issue.  The attached screenshot shows that even though the sketches were made directly on the origin planes in 2D,  I have an angle of 90.9 degrees on one side.  The opposing side is 90 degrees as expected.

Much thanks for taking the time to look at this.

Lee.

[jeff_strater]

You are measuring between two lines, not between two planes.  That measurement is done in the plane defined by those two lines, and because one of them is at an angle, I understand why the angle is not 90 degrees. 

If you measure between the two profiles, you will see 90 (although there appears to be a bug in Measure that shows the wrong dimension in the graphics area

[leekenning]

The sketches were to try to figure out why I have an out-of-square angle but I took it a little further as an exercise to draw the 3d shape with sketches.

This is the model I am making - but I still can't resolve the 90.9 degree angle:

 

[leekenning]