我们得到r=+m=闻+u0日,故 r=ru tru tru6tru0tru e =(-rb)un+(216+r6u 2A 4Ar =(-r62)u,+(2-2+r ")u(假设2) r26(1)=A (-r62)u 2r u u u u ,     r  r  r  r 我们得到 = r + r = r +               u u u u u r r r r r r = r + r + + + u ( )u ( )          r  r r r = − r + 2 + 2 ( )u ( )u ( ) 2 2 4 2 2 3  2  假 设 r Ar r r A r r r r     − = − + + r (r r )u 2   = − 故  r θ  (t) = A 2 2 1