Share 'Trig Problem'

I am making a 3D panel by moving 1 corner of a quad in the Z and then creasing it along the diagonal.  What I am trying to figure out is the relationship between the height and the crease angle between the two triangle faces.   I want to do this so that I can limit the crease angles to something regular (90, 105, 120, etc.)   I can calculate all edge lengths and using right triangles but cant see…