Definition of Derivative for Vector Functions

@nftkashmir197: Q. Is there any role of vectors in electricity and magnetism ?

@amr008: The GeoGebra part around 7:17 made the limiting idea cilck for me, the secant settling into the tangent was great,! Framing the tangent as the secant scaled by 1 over h as h shrinks ties things back to the standard derivative and and keeps the intuition clean. The quick note on the unit tangent as the normalized derivative is handy, my brain did a happy dance. !HUG