To Dimension an Angle

Select the Angular Dimensioning tool.
Set the mode to Angle Size.
Enter a data point to define the dimension start point. The dimension is measured in a counterclockwise direction from this point.
Enter a data point to define a point on the axis.
Enter a data point to define the endpoint of the dimension.
Enter a data point to define the direction and length of the extension line.
Do one of the following:

Go back to step 5 to place another dimension using the same start point.

or
Reset to complete the dimension.

Dimensioning an Angle with Mode set to Size