Polyhedron
Right vs. Oblique

There are two kinds of polyhedra, right and oblique.  A right polyhedron is a figure whose lateral edge is perpendicular to the base of the figure, so the altitude is the length of the lateral edge.  An oblique polyhedron is a figure whose lateral edge is not perpendicular to the base of the figure, therefore the altitude is not a lateral edge of the figure.

right vs oblique

An altitude is a perpendicular segment that joins the planes of the bases.  The height is the length of the altitude.

 

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