a mathematical question about rotation in space...

Hello Blenderheads.
Here is my pb:
Let us imagine 2 objects: one is a cone pointing up and locating at the origine.
The other is located at , say…, (3,4,5).
I can’t find the Euler triple necessary to apply to the cone so that it points TOWARD the other object…
I thought you would easily use some simple cosinus to aplly the z rotation, then idem for Y then for X…But no: my cone ends up facing somewhere else…

Could someone point me to a page or something that explains how to convert a vector to an Euler ?

Mathutils has a function for this - see the Quaternion docs, there is a trackTo funtion.

since you dont want a quat - use someQuat.toEuler()

I ve had a look in the mathutils section and a mixed use of some tools there will be appropriate.
How exciting to learn how to use all that !!!