width always comes first
width
I assume You mean, Which Comes first Height or Width? Typically when speaking its Width First then Height. Example: When someone is describing the resolution of the Computer monitor they may say I have my resolution set at 640 by 480 (640 x 480) This refers to the WIDTH x HEIGHT of the pixels in the resolution (640 Pixels Horizontally/WIDTH & 480 Pixels Vertically/HEIGHT)
it is lxwxh (width x hight)
You can do it whichever way is more convenient for you. The answer is the same either way.
They can come in any order.
Ignore the pendants and assume no conventions..always state clearly your dimensions with unit used (cms or ins.) and orientation i.e. either WxH or HxW or Portrait or Landscape. This way no confusion.. it doesn't take much to be clear but can save a lot of trouble.
Width by height.A standard sheet of typing or copy paper is 8-1/2" by 11"....eight and one half inches wide and eleven inches high. A sheet of legal paper is 8-1/2" by 14".The world standard of DIN A 4 paper is:Width = 21.0 centimeters by height = 29.7 centimeters.
width
The abbreviation for "width" is usually W, as in "H x D x W x", where "H" is height, "D" is depth, and "W" is width, when describing the size of a 3 dimensional object.
You are describing a cuboid, not a rectangle. A rectangle has only two diminutions, length and width.
Volume = Length x Width x Height. If the prism is square, then either Height = Width or Height = Length In the first case, Volume = Length x Width2 and so Width = sqrt(Volume/Length) and Height = Width. In the second case, Volume = Length2 x Width and so Width = Volume/Length2 and Height = Length.