To Create References by Intersecting the Sketching Plane
You can use the 
option to create reference entities by intersecting the sketching plane with surfaces. All other reference entities in Sketcher are created by projecting the referenced geometry onto the sketching plane. In contrast, this option projects the referenced geometry onto the sketching plane to create true intersections. This command is especially useful for variable section sweeps.
option to create reference entities by intersecting the sketching plane with surfaces. All other reference entities in Sketcher are created by projecting the referenced geometry onto the sketching plane. In contrast, this option projects the referenced geometry onto the sketching plane to create true intersections. This command is especially useful for variable section sweeps.1. Click > 
References . The References dialog box opens.
References . The References dialog box opens.2. Click .
.3. Select a surface or an intent surface. Sketcher creates a reference entity at the intersection of the sketching plane with the surface.
4. Click Close.