What is a rotation in geometry?

In geometry, a rotation refers to a transformation that involves turning a figure around a fixed point, known as the center of rotation. This transformation maintains the shape and size of the figure while altering its orientation. The specified point is crucial because it determines the pivot around which the figure will rotate. The angle of rotation indicates how far the figure has been turned, typically measured in degrees.

This definition aligns perfectly with the correct choice, as it accurately describes the operation of rotating a geometric figure. In contrast, the other options pertain to different types of transformations. Sliding a figure describes a translation, changing a figure's size refers to scaling, and a change of shape typically pertains to a transformation that alters dimensions and proportions, such as distortion or shearing. Therefore, the focus on turning a figure about a specific point emphasizes the unique nature of rotation in geometric transformations.