To draw an arc, that is, a segment of a circle:
Select the Arc button .
Press the mouse button (without releasing it) to start the arc, drag the mouse, and release the button to complete it. The direction in which you drag determines which quadrant you draw.
Use the handles midway along each edge of the arc to adjust the angle:
See also:
Selecting, moving and resizing draw objects
For details on other shapes, see Adding a shape.