Trimetric cube drawing in illustrator

I have found many tutorials about drawing isometric cube with illustrator. But I need to do some trimetric cube.
The left part of the image shows the step of drawing isometric cube,
the right part marked questions is exactly I want to know.
What is the scale number and each angle need to be rotated.In this case,the trimetric cube angle is 15 and 30 ,it will be great if there is a formula that can calculate any angle.
Is there anyone can tell me the number in the image? Trimetric cube drawing in illustrator