You use a sine function to model the percentage of the moon's face that is lit by the sun every night. at full moon, all of
the moon's face is lit (100%). at new moon, none of the moon's face is lit (0%)
the output of your function expresses percentages as decimals. for example, 5% = 0.05.
what is the amplitude of your sine function? a)0.1 b)0.5 c)1.0 d)2.0