Final answer:
The line of reflection for triangle ABC is likely the altitude from vertex C to the base AB, which is also the perpendicular bisector, although the question does not explicitly provide this line.
Step-by-step explanation:
To determine the line of reflection that reflects △ABC, we need to identify a line where the triangle can be flipped over to create a mirror image of itself. The characteristics of a line of reflection include being perpendicular to the midpoint of the segment connecting corresponding points in the original figure and its reflection. Given that the sides AB and BC are equal (“AB = BC = r”), we are most likely dealing with an isosceles triangle, which simplifies the problem. In such triangles, the baseline, which is the side that is not equal to the other two (in this case, line AC), is often the key to finding the line of reflection.
According to the information provided, if we consider AB as the baseline, and since AB = BC, the angle at C (“a”) must be the vertex angle of the isosceles triangle. This would imply that the line of reflection could be the altitude from point C to line AB, which would also be the perpendicular bisector of AB, splitting it into equal segments and forming two congruent right triangles along the line of reflection. Since the question does not explicitly give the line of reflection, we may note that the line of reflection is not given.