Geometry for Elementary School/Conventions

Geometry for Elementary School
Glossary Conventions

This appendix summarises the conventions used in this book. There is also a British-American English differences table provided.

Language edit

All the language in this book uses simple British English. Alternative names in American English are listed below.

British English American English Other names
Vertically opposite angles Vertical angles /
The right angle-hypotenuse-side congruence theorem (RHS) The hypotenuse-leg congruence theorem (HL) The hypotenuse-leg-right angle theorem (HLR)
Centre Center /
Compass Compass A pair of compasses (British)
Trapezium Trapezoid /
Centimetre / Millimetre / Metre / Kilometre Centimeter / Millimeter / Meter / Kilometre /
Millilitre / Litre Milliliter / Liter /

Notation edit

This appendix summarises the notation used in the book. An effort was made to use common conventions in the notation. However, since many conventions exist the reader might see a different notation used in other books.


A point will be named by an uppercase letter in italics, as in the point A. In some equations though, it will look like this:  .

Line segment

We will use the notation   for the line segment that starts at A and ends at B. Note that we don't care about the segment direction and therefore   is similar to  .


We will use the notation   for the angle going from the point B, the intersection point of the segments   and  . Sometimes the angle may also be represented by a lowercase letter or even a number, but this is only used in the main text for ease and not in the exercises.


A triangle whose vertices are A, B and C will be noted as  . Note that for the purpose of triangles' congruence, the order of vertices is important and   and   are not necessarily congruent.


We use the notation   for the circle whose center is the point A and its radius length equals that of the segment  .

Note that in other sources, a circle is described by any 3 points on its circumference, ABC. The center, radius notation was chosen since it seems to be more suitable for constructions.

External links

If you are interested seeing an example of past notation, you might be interested in Byrne's edition of Euclid's Elements. See for example the equilateral triangle construction.