Answer:
The "point" is the undefined term needed to define an angle.
Explanation:
Geometry has three fundamental undefined elements: point, straight and flat. One point only has a position in space. It has no dimension (length, width, height). The line is a geometric figure that is generated by a moving point and is formed by the union of points. Finally, a plane is a completely flat surface that has length and width but not thickness. The plane has two dimensions and extends infinitely.
An angle is the portion of the plane between two semi-lines that have the common origin. It is formed by the side (each of the two half-lines) the vertex (point where the two half-lines coincide) and the amplitude (measure of the opening between the sides).
Taking into account what was previously said, you can say that the "point" is the undefined term needed to define an angle. The angle is determined by three points that call it A, B, C, with A ≠ C and B ≠ C, in which one of those points is the vertex. This is shown in the image.