Draw a straight line

In the Toolbox, click Pen .

On the artboard, click once to define the start point, and then click again to define the end point of the line.

Tip:
To constrain the angle of the line to multiples of 45 degrees, hold SHIFT when you click to define the end point of the line.

In the Toolbox, click Line .

Drag from where you want the line to start and release at the point where you want the line to end.

Tip:
To constrain the angle of the line to multiples of 15 degrees, hold SHIFT while drawing the line.