To Measure an Angle
1. Click > . The Measure Angle dialog box opens.
2. In the graphics area, select the start point for the measurement.
3. Press CTRL+Select the second reference. The angle between the two selected references (two straight edges or plane faces) is calculated, and it is displayed in the Results panel and in the graphics area.
4. To measure the supplementary angle, select Measure Supplementary Angle. The measurement and the arc update.
5. To measure the exterior angle, drag the arc to invert it. The measurement updates.
6. Click
.
The measurement is saved to the annotation set. 
Angle. The Measure Angle dialog box opens.