Reflections on a Grid

Look at the following L-shapes drawn on x and y-coordinate axes.

When we reflect a shape in a mirror line, we reflect each corner in turn.

This is done by moving each point directly to the mirror line and then the same distance beyond.

Shape A and Shape B are reflections of each other in the given mirror line.

In the following example, the mirror line is horizontal.

The same technique is used to reflect the shape.