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| | Normal Vector and Curvature |
 | | The tangent line, binormal line and normal line are the three coordinate axes with positive directions given by the tangent vector, binormal vector and normal vector, respectively. |
 | | Thus, the unit-length tangent vector is (-sin(u), cos(u), 0), the binormal vector is (0, 0, 1), and the normal vector is (-cos(u), sin(u), 0). |
 | | Therefore, you are moving in the direction of the tangent vector, your "up" vector is in the direction of the binormal vector and the rate of turning and turning direction are given by the curvature and the direction of the normal vector, respectively. |
| www.cs.mtu.edu /~shene/COURSES/cs3621/NOTES/curves/normal.html (890 words) |
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