Angle is a concept of Geometry to refer to the **space between the intersection of two lines that start from the same point or vertex**, and that is measured in degrees.

The word comes from the Latin *angŭlus*, and is in turn from the Greek ἀγκύλος, which means “hunched over”.

In everyday use, the word angle can also be used as a synonym for corner (in the sense of the incoming angle), for example: “At what angle of the room do you prefer to put the sofa?”; corner or edge: “Beware of the angles of the table: you can hit yourself”; as well as from the point of view: “Have you already assessed the situation from all angles?”

## Types of angles

### According to its opening in degrees

Null angle | It is that formed by two lines that coincide at its vertex and at its ends, therefore, its opening is 0 °. |

Acute angle | It is one with a vertex opening greater than 0 ° and less than 90 °. |

Right angle | It is made up of two semi-lines whose vertex opening is 90 °. |

Obtuse angle | It is one whose vertex opening is greater than 90 ° and less than 180 °. |

Flat angle | It is that constituted by two semi-lines with a 180 ° vertex opening. |

Oblique angle | Also called reflex or concave, it is one that has a top opening 180 ° and less than 360 ° |

Perigonal angle | Also called full angle, it is one that has a 360 ° opening. |

#### Sum of angles

Complementary angles | It is one that, together with another, adds an opening of 90 °. It may be consecutive angles or not in space, but they will be complementary provided that the sum of the degrees of their angles is 90 °. |

Supplementary angles | It is called one that, together with another, adds an opening of 180 °. |

### According to your position

Center angle | It is one whose vertex is in the center of a circle. |

Inscribed angle | The one where the vertex is a point of the circumference, and where it is, in turn, is cut by the semi-straight lines that constitute it. It consists of two ropes of a circle that converge at a common point of the circle forming a vertex. |

Interior angle | The one that is inside a polygon. It is also called the angle whose vertex is in the inner part of the circumference and which is formed by ropes at whose point of intersection a vertex is formed. |

Exterior angle | The vertex is located at a point external to the circumference and its sides are semi-straight that are, in relation to it, in a secant, tangent or both positions. |

Seminscribed Angle | It is the one whose vertex is in the circumference, and is constituted of a rope and a tangent line that converge in the vertex. |