I don't understand why we have to add reasons as to why something is congruent or similar. Is there really any point? If you look at something, and you can see that it is congruent or similar, do you really have to explain why? If you know and the teacher knows, then what is the point? My maths book is full of Doctor Who references, and my ruler has all my fandoms engraved into the wood with pen. What can I say, I was bored in maths :)
JM
JM