Which figure is different from the others: Circle, Square, Triangle, Rectangle?

The figure that is different from the others is the Circle. While the Square, Triangle, and Rectangle are all polygons, defined by having straight sides and angles, the Circle is a unique shape characterized by its curved boundary and lack of corners or edges. This fundamental difference in geometry sets the Circle apart from the other three figures, which are all enclosed shapes with vertices and straight sides.

The Square, Rectangle, and Triangle share key properties as polygons, relating to the number of sides and angles they possess. For instance, both the Square and Rectangle have four sides, while the Triangle has three. The Circle, unlike these shapes, does not conform to the definitions and classifications of polygons, making it the distinct option in this set.