'Facebow Angles' is capable to measure the angle between two lines on any image.
'Facebow Angles' provides the following set of features:
No ads
Angle measurement using two moving straight segments with four touchable balls on ends
Camera preview and image view modes
Screenshots are saved in the database (Album)
Album Image Viewer
Search
and more

Please, find more details, screenshots and videos on the developer's web site.

'Facebow Angles' is intended for Android 4.0 devices (both tablets and phones) and is available in both free and paid ('Pro') versions.
The free version has all but one of the pro version's features -
the number of images in the database is limited to 12 (in 'Pro' version the limit is 360).
Try free version, Enjoy and then Buy 'Pro'!

Screenshots: