Use the Markup Angle tool to measure angles in an image by drawing two intersecting lines at the angle to measure.
To measure angles
From the Image area top toolbar, Markup button menu, select Markup Angle.
Click the start and end points of the first line.
Click the start and end points of the intersecting line.
The obtuse and acute angle values in degrees are displayed.
To change the angle, drag one of the end control points to a new position.
To set the measurement, right-click.
To delete the angle, press the Delete key.