Diagonal

In geometry, a diagonal is a line segment joining two vertices of a polygon or polyhedron, when those vertices are not on the same edge. Informally, any sloping line is called diagonal. The word "diagonal" derives from the ancient Greek διαγώνιος diagonios, "from angle to angle" (from διά- dia-, "through", "across" and γωνία gonia, "angle", related to gony "knee"); it was used by both Strabo and Euclid to refer to a line connecting two vertices of a rhombus or cuboid, and later adopted into Latin as diagonus ("slanting line").

In matrix algebra, a diagonal of a square matrix is a set of entries extending from one corner to the farthest corner.

There are also other, non-mathematical uses.

Non-mathematical uses

In engineering, a diagonal brace is a beam used to brace a rectangular structure (such as scaffolding) to withstand strong forces pushing into it; although called a diagonal, due to practical considerations diagonal braces are often not connected to the corners of the rectangle.

Provença–Diagonal station

Provença is the name of a Ferrocarrils de la Generalitat de Catalunya station located under Avinguda Diagonal and Balmes street. The station is served by FGC-operated Barcelona Metro lines L6 and L7, and Metro del Vallès suburban metro lines S1, S2, S5 and S55. Diagonal is the name of an important station in TMB-operated Barcelona Metro network. It is named after Avinguda Diagonal, where the station is located together with Passeig de Gràcia. It is served by TMB-operated Barcelona Metro lines L3 and L5, and it is also connected with FGC station.

History

FGC

The Ferrocarrils de la Generalitat de Catalunya station was opened in 1882 and in this moment it was not an underground station, but it was located on the same place. In 1929, the current station was opened, under Balmes street and between Provença and Rosselló streets. Currently, it has two accesses from the street, one at each side of the station. In 1995, the hall was extended and some elevators were installed. This hall has some ticket vending machines and some shops. The Rosselló access was opened in 1970 to connect with TMB-operated Barcelona Metro stations and was extended and modernized in 2008.

Glossary of chess

This page explains commonly used terms in chess in alphabetical order. Some of these have their own pages, like fork and pin. For a list of unorthodox chess pieces, see Fairy chess piece; for a list of terms specific to chess problems, see Glossary of chess problems; for a list of chess-related games, see Chess variants.

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

P

[adjective: prophylactic] Prophylactic techniques include the blockade, overprotection, and the mysterious rook move.

Q

R

S

T

U

V

W

X

Z

References

Bibliography