[填空题]
The water depth, D, in metres, in a boating ma6wkfb5iny y ua3zk.,5 rina on a pb k0;ije 4w,6;em6vd8 v e-ny1wsdtckarticular day can be modelled by the fd;nw-wce im e8tv616ke b0dyvs4,;jk unction
D(t)=4sin($30^{\circ}$$\times$t)+12.5,0≤t≤24,where t is the elapsed time, in hours, since midnight.
1.Write down the depth of water at midnight.
2.The cycle of water depths repeats every T hours. Find the value of T. T =
3.(1)Write down the minimum and maximum depths of water during the day. $D_{min}$ = $D_{max}$ =
(2)Find the times at which the minimum and maximum depths of water occur during the day.
4.Draw the graph of D versus t on the grid below.
5.A ship with 8 m draught is allowed to enter the marina if the depth of water is greater than 1010 m. Find the time interval before midday, in hours and minutes, during which the ship is not allowed to enter the marina.
