Question

https://static.k12.com/nextgen_media/assets/8078767-NG_GMT_SemA_01_UT_29.png

What is the equation for the line of reflection that maps the trapezoid onto itself?

Answer 1

Hint:
We're looking for an axis of reflection that maps the figure onto itself, this means that we are looking to reflect about a line of symmetry.
Look for the line of symmetry (count squares if necessary).
Superhint:
The line of symmetry is horizontal.

Answer 2

like the points of the image reflected? @mathmate

Answer 3

Take an example above, the figure, when reflected about the axis of symmetry, will give the figure itself (as if nothing happened).
So for the given figure in your question, you are looking for a line of symmetry so that when reflected it will "map" into itself.
Another way to think of it is the line where if you put a mirror, you would see the complete figure.
Can you suggest where this line should be, by drawing a line in the following diagram?