# Geometry for Elementary School/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.

- Point

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 .

- Angles

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.

- Triangles

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.

- Circles

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.