Vertex in an angle: The point in which the sides of the angle meet. That is, the common endopoint of the two rays.
Vertex angle: The point about which an angle is measured is called the angle´s vertex, and the angle
associated with a given vertex is called the vertex angle.
Vertex in a polygon: The vertices of a polygon are the points where its sides intersect.
Vertex of a cone or a pyramid: The vertex of a cone or a pyramid is the point opposite to the base. That is, the point placed (vertically) above the base.
Vertices of a polyhedron: A vertex od a polyhedron is a point at which three or more edges intersect.
Diagonals in a polygon: The diagonal of a polygon is a line segment that joins two non-consecutive vertices.
The number of diferent diagonals is given by the formula:
where n is the number of sides or vertices.