Use angles to measure the angle in degrees between body features in an image.
1. From the Viewer, select an image.
2. In the Graphics tab of the toolbar, click Angle Measurement 
in the Measurements ribbon.
3. Click on the image where you want the angle to start.
Place the starting point at the edge of the feature that is farthest from the feature angle that you want to measure.
4. Click a second time at the intended position of the vertex (handle).
5. Click a third time where you want the angle to end.
The ending point should be placed at the edge of the second feature.
NOTE: Press and hold the Control key to add a 90 degree angle.