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Modeling with sinusoidal functions: phase shift


The length of the day in Lagos, Nigeria (in minutes), t days since the beginning of the year can be estimated by this formula:
When is the longest day of the year? Give an exact answer.
  • Your answer should be
  • an integer, like 6
  • an exact decimal, like 0.75
  • a simplified proper fraction, like 3/5
  • a simplified improper fraction, like 7/4
  • a mixed number, like 1 3/4
days since the beginning of the year