[size=150]A [b]vector[/b] is a directed line segment with an arrowhead at one end. It has an[b][color=#0000ff] initial point A, where it begins, and a terminal point B, where it ends[/color][/b].[br][list][*]It is defined by three components: [color=#980000][i]magnitude, direction and orientation[/i]. [/color][/*][/list][color=#20124d]To every point [/color][b][color=#0000ff]P[/color][/b][color=#20124d] in a plane there can be assigned a unique vector whose initial point is in the origin [/color][b][i]O[/i][/b][color=#20124d] and the terminal point is in the given point P. This vector [/color][math]\vec{OP}[/math][color=#20124d] is called the [b][i]position [/i][/b]or [b][i]radius [/i][/b]vector of the point P.[/color] [br] [br][b][i]Equal[/i][/b] vectors have the same magnitude, the same direction and the same orientation.[br][b]Opposite [/b]vectors have the same direction but the opposite orientation.[br][br][math]\vec{AA}[/math] is called [b][i]zero - vector[/i][/b] and its [u]magnitude is equal to 0. It has the same the initial and terminal point.[/u][/size]