[填空题]
The average daily hours of5yuxi oqpixl+:ud6 0 ; sunlight, S, during a 12-month period in a particular6 x:yui; 5uo +xql0idpxbl y *rlur.g9 jv;v1ll21hk; towrb1yl *uv hx kl 21;l;vl9g.jrn is 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 =
