Talk:Umbilical point

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What if both curvatures are zero?[edit]

"The sphere is the only surface where every point is umbilic."

What about the plane? —Simetrical (talk • contribs) 19:22, 6 April 2009 (UTC)

Well spotted, indeed every Developable surface has everywhere zero curvature so are also everywhere umbilic. --Salix (talk): 20:04, 6 April 2009 (UTC)