An athlete was having her blood pressure monitored during a workout. Doctors found that her maximum blood pressure, known as systolic, was 90 and her minimum
blood pressure, known as diastolic, was 60. If each heartbeat cycle takes 0.8 seconds,
then determine a sinusoidal model, in the form y=A sin(Bt)+C, for her blood pressure
as a function of time t in seconds. Show the calculations that lead to your answer.