Side length

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The side length is a special case of the length of a line in geometry . The side lengths of a polygon (polygon) are the distances between the respective two corners . The sum of all side lengths is the circumference .

Side length of triangles

Triangle sides in geometry and nature

The length of the sides of the triangle (in the case of flat triangles) is specified in a measure of length (mainly in meters, cm and km). But if you go from the usual geometry to nature or to trigonometric tasks of geodesy , a distinction must be made between horizontal and inclined sides:

Euclidean geometry

  • A well-known Euclidean theorem states that the longest side of a triangle is always shorter than the sum of the other two sides ( triangle inequality ).
  • The larger of two sides of a triangle is always opposite the larger angle. Conversely, the larger of two angles of a triangle is always opposite the longer side.

Plane triangles and their special cases

Right triangle with the right angle at point C.

Spherical triangles

In spherical geometry (spherical geometry), the side length initially corresponds to the length of the corresponding great circle arc . Most of the time, however, the size of the corresponding center angle (in degrees ) is taken as the side length. This definition has the advantage that the radius of the sphere does not matter.

Side length of polygons

The length of the sides of general polygons can be traced back to the calculations on the triangle via the diagonals .