11: Neutral plane Last updated Sep 5, 2021 Save as PDF 10.6: Angles after inversion 11.1: Neutral plane Page ID23653 Anton PetruninPennsylvannia State University ( \newcommand{\kernel}{\mathrm{null}\,}\) 11.1: Neutral plane11.2: Two angles of a triangle11.3: Three angles of triangle11.4: Defect11.5: How to prove that something cannot be proved11.6: Curvature