极坐标情形 y=q() g2(6) de r=q(6 A= 29(0)2e 223 (6)-g1()d6极坐标情形 o x  d  r = ( )  =   A   d 2 [ ( )] 2 1   o x ( ) r =  2  ( ) r = 1   = −   A [ ( )  ( )]d 2 1 2 1 2 2