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?

It is not "prime" in the sense of prime number; $A'$ is A-first, as well as $A''$ is A-second. They are "counters". — Mauro ALLEGRANZA, Jun 26 '19 at 12:56
In the same way, we note the fraction of hours and degrees with minutes (') and seconds (''). — Mauro ALLEGRANZA, Jun 26 '19 at 12:59
See Prime : etymology : "from French prime, from Latin primus (“first”)." — Mauro ALLEGRANZA, Jun 26 '19 at 13:17

Erin Carmody · Accepted Answer · 2019-06-26T13:13:16.960

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).

edited Jun 26 '19 at 13:13

answered Jun 26 '19 at 12:55

Erin Carmody

273

score 0 · Answer 2 · answered Jun 26 '19 at 12:52

0

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 $DEF$.

answered Jun 26 '19 at 12:52

Klangen

5,075

A question about notation of transformations.

2 Answers2