[填空题]
A sailboat is traveling in a straight line given by the parai0g ,xrfa dn41)y g66) vnh ,zohyrj1rmf+*thv ek(t 6wetric equations x=6+4.5 t and y=9 t-11 , where t is the travel time, in hours, after 16:30. The positiv+ v(*ttfwe6kh e x -axis is due east and the positive y -axis is due north. Distances are measured in kilometres.
1. Write down the position of the sailboat at 16:30.(a,b) a= b=
2. (1) Write down the velocity vector of the sailboat.$\begin{pmatrix}
a \\
b
\end{pmatrix}$ a = b =
(2) Find the speed of the sailboat.
A lighthouse is located at $\mathrm{P}(22,0)$ .≈ $km\,h^{-1}$
3. Find the distance of the sailboat from the lighthouse at 19:30.≈ km
4. Find the time, to the nearest minute, when the sailboat is:
(1) closest to the lighthouse;
(2) directly to the north of the lighthouse.
