# Notations

- Page ID
- 10825

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### Notations

\( \bot \) | is perpendicular to |

\( \emptyset \) | The empty set - a set containing no elements |

\( < \) | is less than |

\( > \) | is greater than |

\( \geq \) | is greater than or equal to |

\( \leq \) | is less than or equal to |

\( ! \) | Fractorial |

\( \rightarrow \) | which implies that |

\( \leftrightarrow \) | if and only if |

\( f(x) \) | A function or relation in the variable \( x \) |

\( (a,b) \) |
An ordered pair. This notation can be used in the context of sets describing, the set consisting of all real numbers which lies between \( a \) and \( b \) whenever \( a \) and \( b \) are real numbers. This notation may also be used to denote the coordinates of a point in two dimensions. |

\( \in \) | is an element of |

\( \notin \) | is not an element of |

\( \subseteq \) | is a subset of |

\( \subset \) | is a proper subset of |

\( \cup \) | Union |

\( \cap \) | Intersection |

\( |a| \) | The absolute value of \( a \) |

\( \neq \) | is not equal to |

acute angle | An angle which has measure between \( 0^\circ \) and \( 90^\circ \). |

obtuse angle | An angle which has measure between \( 90^\circ \) and \( 180^\circ \). |

hypotenuse | The side in a right angle which is opposite to the right angle. |

\( \overline{AB} \) | The length of the line segment \( AB \) |

\( \approx \) | is approximately equal to |

\( \sim \) | is equivalent to |

\( \ln(x) \) | Natural logarithm of \( x \). The logarithm of \( x \) to the base \( e \). |

\( \log(x) \) | Common logarithm of \( x \). The logarithm of \( x \) to the base \( 10 \). |

\( \log_a(x) \) | Logarith of \( x \) to the base \( a \), \( a \ne 1 \), \( a>1\) . |

\( \infty \) | Infinity |

\( \alpha \) | The greek letter - alpha |

\( \beta \) | The greek letter - beta |

\( dom(f) \) | The domain of the relation \( f \) |

\( rg(f) \) | The range of the relation \( f \) |

\( \mathbb{R} \) | The set of all real numbers |

\( \mathbb{Q} \) | The set of all rational numbers |

\( \mathbb{Q^c} \) | The set of all irrational numbers |

\( \mathbb{N} \) | The set of all natural numbers |

\( \mathbb{Z} \) | The set of all integers |