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tegenvlak

Tegenvlak is a term used in Dutch geometry to denote the opposite or facing plane relative to a reference plane, often defined by symmetry, position within a solid, or relation to a central point. In many contexts it refers to a plane that is parallel to another plane but located on the opposite side of a body or space.

In prisms and polyhedra with central symmetry, the tegenvlak of a given plane is typically the parallel

One important construction: if a solid has central symmetry with respect to a point O, then the

Context and terminology: tegenvlak is a Dutch term and may not appear in standard English-language geometry

See also: plane, opposite plane, parallelism, central symmetry, polyhedron.

plane
on
the
opposite
side
of
the
figure.
For
example,
in
a
right
prism
the
plane
containing
the
top
base
is
the
tegenvlak
of
the
plane
containing
the
bottom
base.
In
a
cube,
each
face
has
a
tegenvlak,
namely
the
opposite
face
that
is
parallel
to
it.
tegenvlak
of
a
plane
P
is
the
image
of
P
under
a
half-turn
about
O.
This
image
plane
P'
is
parallel
to
P
and
lies
on
the
opposite
side
of
O,
equidistant
from
O
to
the
two
planes.
texts.
Its
general
sense—an
opposite,
parallel
plane
defined
by
symmetry
or
positional
relation—can
be
described
in
English
as
the
opposite
plane
or
the
parallel
plane
on
the
opposite
side
of
a
figure.