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radien

Radien is the plural form of the geometric term radius in several languages, most notably in German where Radien is a common plural. In other languages, such as English, the standard plural is radii, but radien may appear in multilingual texts referring to circles or spheres.

In plane geometry, a radius is a line segment that connects the center of a circle to

Notation and relationships: The radius is denoted by r. For a circle, the circumference is C = 2πr

Etymology and usage notes: The term derives from Latin radius, meaning rod or spoke. In English, the

See also: radius, diameter, circumference, chord, sphere, radial coordinate, radii of curvature.

a
point
on
its
circumference.
In
three
dimensions,
a
radius
extends
from
the
center
to
any
point
on
the
surface
of
a
sphere.
All
radii
of
a
given
circle
or
sphere
have
the
same
length,
called
the
radius,
usually
denoted
r.
and
the
area
is
A
=
πr^2.
For
a
sphere,
the
volume
is
V
=
4/3
π
r^3
and
the
surface
area
is
S
=
4π
r^2.
The
concept
of
a
radius
also
appears
in
related
contexts,
such
as
radial
coordinates
in
polar
and
spherical
systems
and
in
discussions
of
radii
of
curvature
in
geometry
and
optics.
plural
is
radii,
while
in
German
and
some
other
languages
the
plural
radien
is
used;
both
radii
and
radien
are
encountered
in
scientific
writing
depending
on
linguistic
tradition.