Editing Right-hand rule (section)

==Coordinates==
[[Image:Cartesian coordinate system handedness.svg|thumb|left|Left-handed coordinates on the left, <br/> right-handed coordinates on the right.]]
{| class="wikitable floatright"
|+style="text-align:left;"|
For right-handed coordinates, use the right hand.<br/>For left-handed coordinates, use the left hand.
 |- 
! Axis/vector !! Two fingers and thumb !! Curled fingers
|- 
| ''x'' (or first vector) || First or index || Fingers extended
|- 
| ''y'' (or second vector) || Second finger or palm || Fingers curled 90°
|- 
| ''z'' (or third vector) || Thumb || Thumb
|}
For '''right-handed''' coordinates, if the thumb of a person's right hand points along the ''z''-axis in the positive direction (third coordinate vector), then the fingers curl from the positive ''x''-axis (first coordinate vector) toward the positive ''y''-axis (second coordinate vector). When viewed at a position along the positive ''z''-axis, the ¼ turn from the positive ''x-'' to the positive ''y-''axis is '''counter-clockwise'''.

For '''left-handed''' coordinates, the above description of the axes is the same, except using the left hand; and the ¼ turn is '''clockwise'''.

Interchanging the labels of any two axes reverses the handedness. Reversing the direction of one axis (or three axes) also reverses the handedness. Reversing two axes amounts to a 180° rotation around the remaining axis, also preserving the handedness. These operations [[Hyperoctahedral group|can be composed]] to give repeated changes of handedness.<ref name=p345>{{cite web|url=http://www.physics.udel.edu/~watson/phys345/Fall1998/class/1-right-hand-rule.html|title=PHYS345 Introduction to the Right Hand Rule|work=udel.edu |first=George |last=Watson |publisher=University of Delaware |year=1998}}</ref> (If the axes do not have a positive or negative direction, then handedness has no meaning.)