[填空题]
The average daily houx8n 9 +z2-kanv5an g xu/gpem5rs of sunlige0c*ek b3kbwov4: 6 nqf.5k mdht, S, during a 12-month period in a particular town is given byqwefe.6bmkv3c :o40 n* bkk5d 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.