In order to measure non-oriented angle type of AÔB, click on icon .
Click on A, O then B.
If the unity angle of the figure is degree, this measure will lie in the range 0 to 180.
If the unity angle of the figure is radian, this measure will lie in the range 0 to π.
The three points clicked must be named.
If they aren't they will be named by the tool.
In future calculations, this measure will be represented by AOB.