calculating vessel angles

Hello! I tried to use slicer to make reconstruction of intracranial vessels.
After I received the models, I would like to know the angles between the vessels at the bifurcation point.
Are there any way I can access to these information?
The models I have received are mostly like this:
I would like to measure the angles between two vessels.
Thanks a lot!!

Operating system: Windows 10
Slicer version: 5.0.3