A reflection is a type of transformation. It 'maps' one shape onto another.
When a shape is reflected a mirror image is created. If the shape and size remain unchanged, the two images are congruent.
We can describe how a shape has been reflected by saying the equation
of the line it has been reflected in.
The transformation that maps shape A onto shape B is a reflection.
The line is x = 2 because the x-coordinate is 2 for the whole of the line.
The grid below shows a shape. Reflect it in the line y = 1.
Firstly we need to draw the line of reflection, where the
y-coordinate is 1 for the whole of the line.
Now reflect the green shape in this line to give a red shape.