Final answer:
A 180-degree rotation around point C will mirror triangle DEF over point C, maintaining its shape and size but changing its orientation.
Step-by-step explanation:
The student is asking about rotating a geometric figure, specifically a triangle, by 180 degrees around a point. To rotate triangle DEF 180 degrees around point C means every point on the triangle will move to a position directly opposite its current location relative to point C. In terms of geometry, this rotation will result in triangle DEF being mirrored over point C. Each vertex of the triangle will move along an arc that is part of a circle centered at point C, which conceptually is explained by Figure 6.4 as points moving through arc lengths (As) when rotated around a center. It is important to note that a 180-degree rotation is also known as a half-turn, and it does not alter the size or shape of the figure, only its orientation.