The moon's illumination changes in a periodic way that can be modeled by a trigonometric function. On the night of a full moon, the moon provides about 0.25 lux of illumination (lux is the SI unit of

illuminancel During a new moon, the moon provides 0 lux of illumination. The period of the lunar cycle is

29.53 days long. The moon will be full on December 25, 2015. Note that December 25 is 7 days before

January 1,

Find the formula of the trigonometric function that models the illumination L of the moon t days after

January 1, 2016. Define the function using radians.