Moving into the Assembly World - Autodesk Inventor 2010: No Experience Required - page 128

4. Finish the sketch.
5. Start the Rip tool from the Modify tab.
6. Set the Rip Type to Point to Point.
7. Select the triangular face for the Rip Face.
8. Select the two ends of the projected line in the sketch for the Start
Point and End Point.
9. Set the Gap value to .06.
10. Click OK to create the rip.
11. Click the Create Flat Pattern tool. See Figure 3.18.
12. Pick the Go to Folded Part icon at the end of the Flat Pattern tab.
13. Save your work.
FIGURE 3.16 Locating the face to which to apply the Rip feature