Break at Intersection

The Boundary | Edit Polylines | Break at Intersection command breaks a selected polyline at every intersection with another boundary object, such as other curves or areas. If the selected polyline intersects a rectangle, rounded rectangle, or ellipse the curve is not broken. The intersection must occur between a polyline and another boundary object. (You can convert the rectangle, rounded rectangle, ellipse, square, or circle to a boundary object using the Symmetric Shape to Area command and then use this command.) After a polyline is broken, multiple polyline objects are created based on the boundary intersections with the original polyline.

To break a polyline:

Select the polyline that is intersecting with another boundary object.
Click the Boundary | Edit Polylines | Break at Intersection command.

In this example, the polyline is broken into three

polylines since the curve crosses the area twice.