You can change the angle between two segments, or change the length of a segment.
To reshape a straight segment:
Make the shape editable. To learn how, see Editing Shapes.
Red points appear on the shape.
Click a corner point.
To change the angle between the two attached segments, drag the point clockwise or counter-clockwise.
To change the length of one the segments, drag the point outward or inward.
Add more editing points by holding down the [Option](Mac) or [Alt](Win) key while you hold the pointer along the shape's border. When the pointer takes the shape of a pen tip with a plus (+) sign, click where you want to add a new editing point. For more information, see Adding, Deleting, and Moving the Editing Points on a Shape.