Question

A point P is its own image under the reflection in a line l. Describe the position of the point P with respect to the line l.

Answer 1

Since the point, P is its own image under the reflection in the line l. So, point P is an invariant point. Hence, the position of point P remains unaltered.

1. Plot a point P anywhere in the Ist quadrant and reflect this point in the 4th quadrant or y-axis.
2. Draw a line parallel to the x-axis cutting the y' -axis and the line PP'
3. Hence, we observe that an angle of 90 degrees is formed where the line l touches the PP'.
4. Thus, we can conclude that l is the perpendicular bisector of the line PP'.