Which term refers to a flat surface that extends infinitely in all directions within two dimensions?

The term referring to a flat surface that extends infinitely in all directions within two dimensions is a plane. In geometry, a plane is defined as a two-dimensional surface where any two points on the plane can be connected by a straight line that lies entirely within the plane. This infinite nature allows for the representation of geometric figures and concepts within a two-dimensional framework.

In contrast, a line has length but no breadth and extends infinitely in one dimension. A point indicates a specific location in space and has no length, width, or thickness, making it a zero-dimensional entity. An angle, on the other hand, is formed by two rays (or lines) that share a common endpoint, but it does not imply a flat, infinite surface. Understanding the characteristics of these terms is fundamental in geometry, especially when dealing with two-dimensional shapes and their properties.