From Surface Intersection
Extract curves from the intersection of two surfaces.
- 
                On the Geometry ribbon, select the From Surface
                        Intersection tool.

Note: The tool may be hidden in the dropdown menu. To access the dropdown menu, you can do one of the following:- Select 
 at the lower right corner of the
                                currently displayed tool. - Click and hold the currently displayed tool.
 
 - Select 
 - 
                To combine all targets and newly created curves, in the
                    guide bar select Options
                    
, then turn on Combine
                    Curves.
             - 
                The Surface 1 button is active. Click the first
                    surface.
                Tip: To change the first surface, click Surface 1, and then click another surface.
 - 
                The Surface 2 button is active. Click the second
                    surface.
                Tip: To change the second surface, click Surface 2, and then click another surface.
 - 
                Select Apply 
.
                A new curve is created from the intersection of the two surfaces. - Right-click and mouse through the check mark to exit, or double-right-click.