We introduce the fourth fundamental form of the torus hypersurface in the four dimensional Euclidean space. We also compute I, II, III and IV fundamental forms of a torus hypersurface.

We study curvature formulas and the fourth fundamental form IV of hypersurfaces in the four dimensional Euclidean geometry E4. We calculate fourth fundamental form and curvatures for hypersurfaces, and also for hypersphere. ...

We study the fourth fundamental form of the factorable hypersurface in the four dimensional Euclidean space E4. We obtain I, II, III, and IV fundamental forms of a factorable hypersurface.