Answer Happy

The brightness of some stars can fluctuate over time. Suppose that the brightness of a certain star can be modeled by the following. B (t) = 7.5 +10.5 sin 21 67 In this equation, B (t) represents the magnitude of brightness, and t is the time (in days). Suppose we start at t = 0 days. During the first 67 days, when will the star's magnitude of brightness be 13? Do not round any intermediate computations, and round your answer(s) to the nearest day. (If there is more than one answer, enter additional answers with the "or" button.) t = 1 days or Х 5 ?