The number of hours of daylight in City A is given by the fo
     The number of hours of daylight in City A is given by the following equation, where x is the number of days after January 1. Within a year, when does City A have 12 hours of daylight? Give your answer in days after January 1.  y = 3 sin [2 pi/365 (x - 79)] + 12  days  (Use a comma to separate answers as needed. Round to the nearest integer as needed.) 
  
  Solution
we have given the number of hours of daylight in city A is given by y=3sin((2pi/365)(x-79))+12 and 12 hours day light
y=3sin((2pi/365)(x-79))+12
12 =3sin((2pi/365)(x-79))+12
3sin((2pi/365)(x-79))=0
sin((2pi/365)(x-79))=0
(2pi/365)(x-79)=arcsin(0)=0,when sin0=0,sin(pi)=0 and sin(2pi)=0
when arcsin(sin0) =0 and arcsin(sin(pi)) =0
(2pi/365)(x-79) =0
x=79
when arcsin(sin(pi)) =pi
(2pi/365)(x-79)=pi
x=(365/2)+79=261.5
x=261
when arcsin(sin(2pi)) =2pi
so x=79,261 days

