How do you know?
Does this picture show a reflection? Yes! How do you know?
I know because....the figure and it's image are:
1. congruent
2. facing opposite directions
3. the same distance from the mirror line
I know because....the figure and it's image are:
1. congruent
2. facing opposite directions
3. the same distance from the mirror line
This is what would be required to explain "How do you know?" when answering a question about reflections!