Steps:
1.	Click on the reference line.
2a.	Click on an arc.
fi	A tangent is drawn on the arc parallel to the reference line.
Note:
The position where you click the arc defines the positon of the parallel line.
2b.	Click on a second line which is parallel to the reference line.
3b.	Enter a number.
fi	That number of parallel lines is drawn between the two selected lines.