My teacher wrote an alternative equation on the board for curvature, and I am wondering how it is true:(adsbygoogle = window.adsbygoogle || []).push({});

k = | dT/dt / |dR/dt| |

where T is the unit tangent vector.

I know k = |R' x R''| / |R'|^3 = |dT/ds|

but I am not sure about the formula in question. How is it true/derived?

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# Curvature in terms of the tangent vector

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