Functional Design Using Design Accelerators - Autodesk Inventor 2010: No Experience Required - page 360

FIGURE 7.52 Selecting the stationary reference
4. When you select the stationary reference, all the bends on the part
highlight. Pick only the large bend that was split.
5. After a moment, a preview appears (Figure 7.53) to show the result of
unfolding the large bend. Click OK to create the Unfold feature.
FIGURE 7.53 A preview of the Unfold feature
6. Create a new 2D sketch on the unfolded face.