start of a demonstration of Euler and Meusnier

Euler_Meusnier.py

var('u v t s')

P = parametric_plot3d([cos(u)*sinh(v), sin(u)*sinh(v), cosh(v)], [u,0,2*pi], [v,0,2], opacity=0.6, aspect_ratio=1, color='blue')
P+= parametric_plot3d([cos(u)*sqrt(3), sin(u)*sqrt(3), 2], [u,0,2*pi], thickness=2, color='black')
P+= parametric_plot3d([0, sinh(v), cosh(v)], [v,0,2], thickness=2, color='red')



P.show()