Definition:Orientation of Coordinate Axes/Cartesian Plane/Left-Handed

Definition
A Cartesian plane is defined as being left-handed if it has the following property:

Let a left hand be placed, with palm uppermost, such that the thumb points along the $x$-axis in the positive direction, such that the thumb and index finger are at right-angles to each other.

Then the index finger is pointed along the $y$-axis in the positive direction.


 * Left-hand-cartesian-plane.png

Also see

 * Definition:Right-Handed Cartesian Plane