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RE: How do u go about doing this---?

• To: mathgroup@smc.vnet.net
• Subject: [mg10921] RE: [mg10844] How do u go about doing this---?
• From: "Barthelet, Luc" <lucb@ea.com>
• Date: Thu, 12 Feb 1998 20:16:02 -0500

F[x_,y_]:=(Sin[x]+Cos[y])/(Sin[x]-Cos[y]); Simplify[
D[F[x,y],x]^2+D[F[x,y],y]^2 ]

returns the appropriate result.


>-----Original Message-----
>From:	McAllister [SMTP:lmcallister@email.msn.com]
To: mathgroup@smc.vnet.net
>Sent:	Tuesday, February 10, 1998 6:02 PM
>To:	mathgroup@smc.vnet.net
>Subject:	[mg10844] How do u go about doing this---?
>
>
>Let f(x) = sin(x)+cos(y)
>                -----------------
>                sin(x) - cos(y)
>
>Show that
>                (df/dx)^2 + (df/dy)^2    =
>
>                2+cos(2(x-y))+cos(2(x+y))
>                -----------------------------------
>                            (sin(x)-cos(y))^4
>
>
>Thanks,
>
>L.
>
>
>