[填空题]
The average daily hours of sunlight,eyf 1,a( 1( oypwsfh2g S, duridp mcqj3yrh+ +,9o w-ang a 12-month period in a particular to,mcj daw3 h+-+qp9o yrwn 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.b = $^{\circ}C$
3.Write down the values of t when the average daily sunlight is 10 hours.