Line of Symmetry in a Reflection?

📌 CONCEPT: The line of symmetry of a figure is a line that divides the figure into two halves that are mirror images of each other, with corresponding parts being congruent.

📐 RULE / FORMULA: The perpendicular bisector of a line segment is the line that passes through the midpoint of the segment and is perpendicular to the segment. In this case, line AB is the perpendicular bisector of PQRS.

💡 WORKED EXAMPLE: Given a line segment PQ of length 10 cm, if it is reflected in the line AB, then AB is the line of symmetry of the triangle PQR. This is because AB is the perpendicular bisector of PQ, and it divides the triangle into two congruent halves.

⚠️ COMMON MISTAKE: Students may mistakenly conclude that the line of symmetry is the line that passes through the middle of the triangle, rather than the perpendicular bisector of the line segment.