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1 0 For the surface $sigma(u,v)= (frac{cos v}{cosh u}, frac{sin v}{cosh u}, tanh u)$ , compute the geodesic curvature and the normal curvature of: (i) a meridian $v$ = constant, (ii) a parallel $u$ = constant. Which of these curves are geodesics? I know that a meridian is a geodesic and its geodesic curvature $kappa_g = 0$ . From the textbook, the normal curvature $kappa_n = gamma''·N$ and the geodesic curvature $kappa_g = gamma'' · (N times gamma')$ , where $N$ is the unit normal of the surface, and $gamma$ is a unit-speed curve in $mathbb{R}^3$ . How can I find the $gamma$ in the formula? Thanks! differential-geometry curvature geodesic share | cite | improve