Un regalito... el 3. a)   de nada!!! :) xD





> f:=x->(R*sqrt(x))/sqrt(H);
> 

                                   R sqrt(x)
                         f := x -> ---------
                                    sqrt(H)

> Vrev:=Pi*int(f(x)^2,x=0..1);

                                          2
                                      Pi R
                          Vrev := 1/2 -----
                                        H

> R:=1;

                                R := 1

> H:=1;

                                H := 1

> Arev:=2*Pi*int(f(x)*sqrt(1+(diff(f(x),x)^2)),x=0..1);

                  Arev := 2 Pi (5/12 sqrt(5) - 1/12)

> evalf(Arev);

                             5.330413502

>