Can you tell that the left side is a mirror image of the right side?
If you have a mirror with you, you can try this experiment to see the mirror image. Otherwise you will have to just imagine doing the experiment.
Hold the mirror up to the paper with the mirror facing left. The mirror should be perpendicular to the paper as in the picture below.
Put the straight edge of the mirror along the line down the center of the letter A:
Now look into the left side of the mirror diagonally. You should see the left side of the letter A and its reflection in the mirror. Notice that these two things together make up the letter A!
Now take a look at the picture of the letter B below.
This time line the mirror up horizontally across the center of the letter:
Notice that the top half is a mirror image of the bottom half.
If we can draw a line on a picture that splits it in half so that one side of the line is a mirror image of the other, we say that the picture has reflection symmetry.
The place where you draw the line is called the line of reflection. Draw the line of reflection for each of these pictures: