# Distances/Vectors

In mathematics and physics, a **vector** is a quantity having direction as well as magnitude, especially as determining the position of one point in space relative to another.

## Theoretical vectors[edit]

**Def.**

- "a quantity that has both magnitude and direction"
^{[1]} - "the signed difference between two points"
^{[2]}or - an "ordered tuple representing a directed quantity or the signed difference between two points"
^{[2]}

is called a **vector**.

## Unit vectors[edit]

**Notation:** let denote a unit vector in the ith direction.

**Def.** a "vector with length 1"^{[3]} is called a **unit vector**

## Force vectors[edit]

A force vector is a force defined in two or more dimensions with a component vector in each dimension which may all be summed to equal the force vector. Similarly, the magnitude of each component vector, which is a scalar quantity, may be multiplied by the unit vector in that dimension to equal the component vector.

where is the magnitude of the force in the ith direction parallel to the x-axis.

## Triclinic coordinate systems[edit]

A triclinic coordinate system has coordinates of different lengths (a ≠ b ≠ c) along x, y, and z axes, respectively, with interaxial angles that are not 90°. The interaxial angles α, β, and γ vary such that (α ≠ β ≠ γ). These interaxial angles are α = y⋀z, β = z⋀x, and γ = x⋀y, where the symbol "⋀" means "angle between".

## Monoclinic coordinate systems[edit]

In a monoclinic coordinate system, a ≠ b ≠ c, and depending on setting α = β = 90° ≠ γ, α = γ = 90° ≠ β, α = 90° ≠ β ≠ γ, or α = β ≠ γ ≠ 90°.

## Orthorhomic coordinate systems[edit]

In an orthorhombic coordinate system α = β = γ = 90° and a ≠ b ≠ c.

## Tetragonal coordinate systems[edit]

A tetragonal coordinate system has α = β = γ = 90°, and a = b ≠ c.

## Rhombohedral coordinate systems[edit]

A rhombohedral system has a = b = c and α = β = γ < 120°, ≠ 90°.

## Hexagonal coordinate systems[edit]

A hexagonal system has a = b ≠ c and α = β = 90°, γ = 120°.

## Cubic coordinate systems[edit]

A cubic coordinate system has a = b = c and α = β = γ = 90°.

For two points in cubic space (x_{1}, y_{1}, z_{1}) and (x_{2}, y_{2}, z_{2}), with a vector from point 1 to point 2, the distance between these two points is given by

## Hypotheses[edit]

- For a vector, the direction can be stated and the magnitude is arbitrary.

*See also: Control groups, Proof of concept, and Proof of technology*

## See also[edit]

## References[edit]

- ↑ Paul G (22 December 2003).
*vector*. San Francisco, California: Wikimedia Foundation, Inc. https://en.wiktionary.org/wiki/vector. Retrieved 2015-08-10. - ↑
^{2.0}^{2.1}*vector*. San Francisco, California: Wikimedia Foundation, Inc. 24 July 2015. https://en.wiktionary.org/wiki/vector. Retrieved 2015-08-10. - ↑
*unit vector*. San Francisco, California: Wikimedia Foundation, Inc. https://en.wiktionary.org/wiki/unit_vector. Retrieved 2015-08-10.