A question about notation of transformations.

Question

Let’s say we translate a triangle ABC to the triangle A’B’C’, my question is, how do we say A’B’C’?

I believe it is said A prime, B prime, C prime, but why are we using the word prime here? Any connection with prime numbers or just a coincidence of the English language?

Answer 1

The symbol ' is called prime, the same word used to describe non-composite numbers. The first meaning is used in your question a way to use the same letter twice, to describe a different point or angle which might be related to A (maybe they are similar triangles). The prime is also sometimes used for derivatives, calling the derivative of $f$ by $f'$ ($f$ prime).

Answer 2

It has nothing to do with prime numbers. It's just an alternative way of describing the translated shape. You could also simply call it $DEF$.