See more of Escher's work at the sight where I got this image. Here is a link to down load a lesson plan with instructions and some explorations of the properties. By 1881 the properties of the one-sided figure were being used in a magic trick called the Afghan band. Another nice link for teachers and students is this article by Ivars Peterson about the relationship between Mobius bands and recycling. Oblique is used to refer to something other than a right angle.
Triangles withou a right triangle are rightfully called oblique triangles.
Two intersecting lines that are neither parallel or perpendicular are called oblique. The common usage is related to something that is slanted or inclined. Ogive The statistical term ogive refers to a cumulative distribution function. The term was applied by Francis Galton to the cumulative normal distribution but is used more generally now. The word originally comes from a term in architecture for a diagonal rib of a Gothic vault or a pointed arch.