L23A 1. Derivation: Equations of Weingarten L23B 1. Derivation: Equations of Weingarten (cont.) 2. Gauss Curvature in terms of the First and Second Fundamental Form L23C 1. Mean Curvature in terms of the First and Second Fundamental Form 2. Principal Curvatures in terms of the First and Second Fundamental Form 3. Proposition: Smoothness of Gauss Curvature, Mean Curvature and Principal Curvatures