王士 D2:a≤≤B,0≤rsφ(6) f(rcos 0, rsin e)rdrde B p(6) de f(rcos8, rsin O)rdr 0 D3:0≤6≤27,0≤r≤q(6) (rcos6, sino)rdrde ∫( D3 2丌 q(6) =|d6 f(rose, rsin A)rdr 0 反回( cos , sin ) . ( )  0      d f r  r  rdr : , D2      0  r  ( ).  2 ( cos , sin ) D f r  r  rdrd  3 ( cos , sin ) D f r  r  rdrd ( cos , sin ) . ( ) 0 2 0      d f r  r  rdr : 0 2 , D3     0  r  ( )