An angle is formed when two different rays are joined at a common endpoint called vertex.
The intersection or where the two rays meet is called the vertex of the angle. In this case, it is vertex \(E\).
The angle above can be called simply by its vertex, thus \(\angle E\). It can also be named by using three points found on the angle. But make sure that the middle point is the vertex. So the angle above can be named as \(\angle KEM\) or \(\angle MEK\). It is wrong to name it as \(\angle EMK\) or \(\angle MKE\).
In addition, the sides of the angle are the rays \(\overrightarrow{EK}\) and \(\overrightarrow{EM}\).