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. at the lower right corner of the
                                currently displayed tool.
- Click and hold the currently displayed tool.
 Tip: To find and open a tool, press Ctrl+F. For more information, see Find and Search for Tools.
- Select 
- 
                To combine all targets and newly created curves, in the
                    guide bar select Options
                     , then turn on Combine
                    Curves. , 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. .
                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.