直接计算法比较 曲线积分 对坐标的曲线积分方法:一代二换三定限 LP(x, y)dx+o(x,y)dy ly=y(t) 从a→B PPIPIp(0), v(tlo'()+2lp(6),y(t)ly'(t)]dt P(x,y,z+Q(x,y,)小+R(x,y,孔)d x=p(t z =o(t) ∫Pg(,(),m()l'( t从a→>Ba +QIq(t,y(t),m(t)y(t)+Rp(t),y(t),m(t)lm'(t)t直接计算法比较 一、曲线积分 对坐标的曲线积分 P x y dx Q x y dy C ( , ) + ( , )   P t t t Q t t t dt y t x t t { [ ( ), ( )] ( ) [ ( ), ( )] ( )} ( ) ( )             ====  +   = = 从 → 方法：一代二换三定限 P(x, y,z)dx + Q(x, y,z)dy + R(x, y,z)dz  Q t t t t R t t t t dt P t t t t z t y t x t t [ ( ), ( ), ( )] ( ) [ ( ), ( ), ( )] ( )} { [ ( ), ( ), ( )] ( ) ( ) ( ) ( )                    +  +  ====       = = = 从 →