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## Main Question or Discussion Point

I was reading the Wikipedia article about this, and I've noticed something that doesn't seem to make sense:

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

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

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

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?