Draw a square on a sheet of paper. Using a plane mirror, locate its axes o reflection symmetry. Verify that in addition to the two diagonals, there are two other such axes that pass through the center of the square with the mirror parallel to a side of the square. Two of the positions in which the mirror can be placed are shown in Fig. 14, together with a plane drawing in which all four axes are indicated by dashed lines.
Now, notice that a square is a rectangle. So, a rectangle cannot have more than the 4 axes of symmetry that a square has. However, check if the diagonals of rectangle, which is not a square, can be axes of symmetry.