A rotation has taken place when a figure is moved around a fixed point called the center of rotation. Each vertex must move the same degree and direction around the center of rotation. Each vertex must be the same distance from the center. In this image, you could tell that a rotation has occurred without using a grid or coordinate plane by realizing that there is a center of rotation (which is a fixed point) that when you draw a line from vertex C to point F and C' to F, it creates a 90 angle which represents a rotation 90 counter clockwise. This is a rotation because the object is moved around point F, while each vertex on the image is moved 90 in a counter clockwise direction. This is not a reflection because there is no line of reflection and the image does not reflect over a line but rotate over a point. Therefore, this is a rotation 90 over around point F which is located at (-1,0).