[填空题]
A boat, whose speed in still water is 1. osbnpd+0f/.o 7 c xjzy1(pgeu :sbk;2 5*kzsg /xf2t5e5 m/s, must aim upstream at an angle ofkzbpj */csg 25;e5t :uyg(xz kfex21s $26.3^{\circ}$ (with respect to a line perpendicular to the shore) in order to travel directly across the stream. (a) Determine the speed of the current. $m/s$ (b) Determine the resultant speed of the boat with respect to the shore $m/s$
