Definition:Orientation of Coordinate Axes/Cartesian 3-Space
This page is about orientation of Cartesian 3-space in the context of analytic geometry. For other uses, see Orientation.
Definition
There are $2$ different orientations of a Cartesian $3$-space:
Right-Handed
A Cartesian $3$-Space is defined as being right-handed if it has the following property:
Let a right hand be placed such that:
- the thumb and index finger are at right-angles to each other
- the $3$rd finger is at right-angles to the thumb and index finger, upwards from the palm
- the thumb points along the $x$-axis in the positive direction
- the index finger points along the $y$-axis in the positive direction.
Then the $3$rd finger is pointed along the $z$-axis in the positive direction.
Left-Handed
A Cartesian $3$-Space is defined as being left-handed if it has the following property:
Let a left hand be placed such that:
- the thumb and index finger are at right-angles to each other
- the $3$rd finger is at right-angles to the thumb and index finger, upwards from the palm
- the thumb points along the $x$-axis in the positive direction
- the index finger points along the $y$-axis in the positive direction.
Then the $3$rd finger is pointed along the $z$-axis in the positive direction.
Also known as
The orientation of a Cartesian coordinate system is known as its handedness.
The term arises from whether it is defined as a left-handed system or a right-handed system.
Sources
- 1936: Richard Courant: Differential and Integral Calculus: Volume $\text { II }$ ... (previous) ... (next): Chapter $\text I$: Preliminary Remarks on Analytical Geometry and Vector Analysis: $1$. Rectangular Co-ordinates and Vectors: $1$. Coordinate Axes
- 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): orientation
- 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): orientation