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https://en.wikipedia.org/wiki/Frenet–Serret_formulas

The article says that the unit vector for the tangent direction is:

**T**= ( d

**r**/ ds ) / | d

**r**/ ds |

OK, that's the standard way to express a unit vector, but it seems that in this case, | d

**r**/ ds | is 1, so what is the point of including this term?