Descriptive Geometry challenge

[saz]

This exercise may be easy for some experts, but for regular students (like me) you'll get some smoke out of those heads! =)

The objective is pretty simple: "Determine an oblique plane (double-projection) that does an angle of 60º with the horizontal plane and 40º with the vertical plane"

Hint: Use the lines of greater inclination and greater decliveI haven't managed to do it yet, so I'd appreciate someone who could help me by giving some orientation or if possible a "scan" of the completed exercise.(sorry for my bad english)

 

[HallsofIvy]

Since this has nothing to do with either Tensor Analysis or Differential Geometry, I am moving it to "General Math".