Find the angles between two solids

I have 2 solids (A and B) and I need to find the three angles between their x, y, and z axes. If I calculate the geometrical center of the two solids (Ax, Ay, Az and Bx, By, Bz), is it correct to calculates the angles between their axes as follow?

Thank you

$$\Delta x = Ax - Bx$$

$$\Delta y = Ay - By$$

$$\Delta z = Az - Bz$$

$$\angle x = a\tan 2(\Delta x, \sqrt{\Delta y^2 + \Delta z^2})$$

$$\angle y = a\tan 2(\Delta y, \sqrt{\Delta x^2 + \Delta z^2})$$

$$\angle z = a\tan 2(\Delta z, \sqrt{\Delta x^2 + \Delta y^2})$$

Angle between solids has no meaning. We can have an intersection angle between two planes.

• Hi Narasimham, thank you. Of course I expressed myself badly. How can I calculate the angles between the planes defined by their axes ? – clusterman Oct 26 '18 at 9:51
• Define lines of intersection. Find angle between normals of two planes (at a time) at any convenient point on a line of intersection. – Narasimham Oct 26 '18 at 9:56
• Thank you again for your time @Narasimham. So, is my attempt correct? Or I totally missed the point here ? – clusterman Oct 26 '18 at 10:34
• See, if it makes sense in some way I would go that way else I choose all pairs of planes. – Narasimham Oct 26 '18 at 10:45
• Thank you for your clear and detailed answer @Narasimham. Have a nice day – clusterman Oct 26 '18 at 12:39