6. The summer and winter solstices are the longest day and night of the year, respectively. The summer solstice happens between June 20 and June 21, while the winter solstice is between December 21 and December 23. At a latitude of 56 the summer solstice is 18 hours long and the winter solstice is 17.5 hours long. Write a sinusoidal equation modeling the hours of daylight in a year. Use t for the variable and measure t in weeks. For the purposes of this problem, idealize a year to be 52 weeks long, with the winter solstice a week before the new year.