[填空题]
The average daily hours of sunlight, S, during es1t3tkew8;2w 6xm/jx ywki2a 12-month period in a particulaa1 fjvr+:3o ixr town is ao1vj+f3rxi: given by the function
S(t)=acos(bt−π)+d,where time, t, is measured in months, a and d are constants, and b is measured in degrees.
The graph of S versus t is shown in the diagram below.
1.Find the value of
(1)a;
(2)d.
2.Find the value of b. $^{\circ}$
3.Write down the values of t when the average daily sunlight is 10 hours.
t =
