[填空题]
The water depth, D, in metres, ind/5-6k q8ycb(tg, n4 ftyp nref-21g,ee vntwf4-varn 5 r0rq a harbour on a particular day can be modelled by the equatior,w g-f42nf0r te avenvr51-qn
D=2.5cos($30^{\circ}$$\times$t)+5, 0≤t≤24,
where t is the elapsed time, in hours, since midnight.
1.Draw the graph of D versus t on the grid below.
2.Find the lowest and highest depths of water in the harbour, and the times when they occur. $D_{min}$ = t = ; $D_{max}$ = t =
3.A large yacht has a draught of 3 metres. Decide whether the yacht will be able to enter the harbour at 5 pm.
