Vectors Definition. Main information
Definition. Vector is a directed line segment, ie the segment having a length and a definite direction. Graphically vector depicted as a directed line segments of a certain length. (Fig. 1)
The vector which has a beginning point A and end point B, denoted AB (Fig. 1). Also, the vector represent one small letter, for example a.a.
The length of the directed segment determines the numerical value of the vector and is called the length of the vector AB
The length of the vector AB is denoted as: |AB|.
Definition. Zero vector is a vector whose start and end points coincide.
The zero vector is usually is denoted as 0.
The length of the zero vector is zero.
Vector parallel to one line or lying on one line are called collinear vectors
Definition. Two collinear vectors a and b are called codirected vectors if their directions are the same: a↑↑b (Fig. 3).
Oppositely directed vectors
Definition. Two collinear vectors a and b are called oppositely directed vectors if their directions are opposite: a↑↓b (Fig. 4).
Vectors parallel to the same plane, or lie on the same plane are called coplanar vectors
It is always possible to find a plane parallel to the two random vectors, in that any two vectors are always coplanar.
Definition. Vectors a and b is an equal vectors if they are in the same or parallel lines, their directions are the same and the lengths are equal (Fig. 6).
Two vectors are equal if they are collinear, codirected and have the same length:
a = b, if a↑↑b and |a| = |b|.
Definition. Unit vector or orth is a vector whose length is equal to one.