[填空题]
A sailboat is traveluzw;8l,w tcz f)8(rct5b i5eling in 969at z jmu r k 8w)h4v9q7i7s-taqqeva straight line given by the parametric equations x=6+4.5 t and y=9 t-11 , where t is the travel tim t67 9)jt 7vs9quqviaaq9ekw4r z-8hme, in hours, after 16:30. The positive 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.
