Chapter 4.5, Problem 81PE

In the theory of biorhythms, sine functions are used to measure a person's potential. You can obtain your biorhythm chart online by simply entering your date of birth, the date you want your biorhythm chart to begin, and the number of months you wish to have included in the plot. Shown below is your author's chart, beginning January' 25,2015. when he was 25,473 days old. We all have cycles with the same amplitudes and periods as those shown here. Each of our three basic cycles begins at birth. Use the biorhythm chart shown to solve Exercises 75-82. The longer tick marks correspond to the dates shown.

If you extend these sinusoidal graphs to the end of the year, is there a day when your author should not even bother getting out of bed?