Re: Deriviation d/dt(x(t))

*To*: mathgroup at smc.vnet.net*Subject*: [mg27438] Re: [mg27407] Deriviation d/dt(x(t))*From*: Reza Malek-Madani <research at usna.edu>*Date*: Sun, 25 Feb 2001 20:55:42 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

Hi Chrsitian: I think you want to try something like D[x[t]^2+y[t]^2==r^2,t] Reza. ------------------------------------------------------------------------- Reza Malek-Madani Director of Research Research Office, MS 10m Phone: 410-293-2504 (FAX -2507) 589 McNair Road DSN: 281-2504 U.S. Naval Academy Nimitz Room 17 in ERC Annapolis MD 21402-5031 Email: research at usna.edu -------------------------------------------------------------------------- On Sun, 25 Feb 2001, Christian Maier wrote: > I have a problem, having a definition of a circle: x^2+y^2=r^2 > Where x and y are functions of the time: x(t), y(t) and r ist a constant. > > Now I want to deriviate the equation to get the velocity vector. > It should be : 2 x dx/dt +2 y dy/dt = 0 > > Can anyone tell me how to do? > Thans in advance! > > Christian Maier > > > > >