Definition: Angles are created at the intersection between two lines. As seen in the following illustration
![Angles are created at the intersection between two lines](/_ipx/f_png,s_500x502/https://cdn.tutorela.com/images/Los_angulos_se_crean_en_la_interseccion_entre_.width-500.png)
The angle in the illustration is called . We could also call it angle . The important thing is that the middle letter is the one at the intersection of the lines.
For example, in this case:
![We could also call it angle ABC](/_ipx/f_png,s_500x502/https://cdn.tutorela.com/images/Tambien_podriamos_llamarlo_angulo_ABC.width-500.png)
The angle is or . Both notations are correct for the same angle.
We usually mark the angle with an arc as follows:
![The angle is BCD](/_ipx/f_png,s_500x502/https://cdn.tutorela.com/images/El_angulo_es_BCD_o_DCB.width-500.png)
The marked angle is . Sometimes we will denote angles using Greek letters, for example:
or
Before the name of the angle, we should note the angle symbol, like this:
Together it looks like this:
or
Next, we will delve into the size of angles, the different types, and those that are created when a line intersects two parallel lines.