Are all circles similar and y?

Answer 1

First let me point out the difference between similarity and congruence. Let me consider 2 identical circles that have been drawn on 2 separate tracing papers, now imagine that i overlap the 2 tracing papers. Will you now only see one? Yes! Hence we can say they are congruent.

But if i consider 2 different circles, on the tracing paper, it won't turn out so well. But we would notice that they would be IDENTICAL if we resize one of them (assuming they are in the same orientation).

That is the most simplest way i can explain the difference and in that way, hopefully what it means to be similar.

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NOW moving back to the question... imagine 2 different circles, even though they are different, we will still observe that the are identical if, again we resize one of them. Hence all circle are similar no matter how big or small. Because, when it comes to comparing shapes based on similarity, size doesn't matter.

(from someone who has just done a math chapter on similarities and congruence of triangles)