An experiment with a torch
Part 2.

Set up the experiment as shown in the image above. The mirror is set vertically. The slice of paper should be parallel towards the mirror. Try to focus the light of the torch through the crack in order to hit the right edge of the mirror. There, the light should be reflected and hit the right edge of the paper (see image above). Maybe you might have to arrange the paper a little bit towards the left or right in order to succeed.

The paper remains at this place. Rearrange your torch in order to hit the crack and the left edge of the mirror. There, the light should be reflected. As you can see, the reflected light does not hit the paper any more (see picture above).

Rearrange the torch in order to hit the left edge of the paper with the light (see picture below). Mark the mirror at the spot where the light hits it and is reflected. Measure the size of the distance between the tight edge and your mark on the mirror. That is the size that the mirror should be to picture the whole slice of paper.

Compare the length of the mirror between the right edge of the mirror and your mark with the length of your paper. What can you say about that?

The distance between the right edge of the mirror and the mark is exactly...

...twice the length of the paper!
...three times the length of the paper!
...half the size of the paper!