[填空题]
The average daily hours of su.5bj+c ((p g rqd89bbfh3bmnbnlight, S, during a 12-nyrmf e9-c -n . ccvit-vko576month period in a particular town is given by the functionoik5-96mc ry7v--e f tcnc.nv 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 =
