What is the Definition of Cartesian coordinate system?

Answer 1

A system for identifying points on a plane or in space by their coordinates is called a Cartesian coordinate system.

In a plane (2-dimensional), the Cartesian coordinate system is determined by the two perpendicular directed lines Ox as x-axis, and Oy as y-axis (where the point of intersection O is the origin) and the given unit length.

For any point P in the plane, let M and Nbe points on the x-axis and y-axis such that PM is parallel to y-axis and PN is parallel to x-axis. If OM = x and ON = y, then (x, y) are the coordinates of the point P in this Cartesian coordinate system.

Normally, Ox and Oy are chosen so that an an anticlockwise rotation of one right angle takes the positive x-direction to the positive y-direction.

In 3-dimensional space, the Cartesian coordinate system is determined by the three mutually perpendicular directed lines Ox as x-axis, and Oy as y-axis,and OZ as z-axis (where the point of intersection O is the origin).

For any point P in a space, let L be the point where the plane through P, parallel to the plane containing the y-axis and z-axis, meets the x-axis. Alternatively, L is the point on the x-axis such that PL is perpendicular to the x-axis. Let M and N be points on the y-axis and z-axis. The points L, M, and N are in fact three of vertixes of the cuboid with three of its edges along the coordinate axes and with O and P as opposite vertixes. If OL = x and OM = y, and ON = z, then (x, y, z) are the coordinates of the point P in this Cartesian coordinate system.