Prove-d-dt-e-e-d-dt-e-e-where-dots-denote-differentiation-with-respect-to-time-t-

Question Number 6644 by WAI LIN last updated on 07/Jul/16

P r o v e \frac{d}{d t} e_{ρ} = ϕ e_{ϕ}, \frac{d}{d t} e_{ϕ} = - ϕ e_{ρ} w h e r e d o t s d e n o t e

d i f f e r e n t i a t i o n w i t h r e s p e c t t o t i m e t .