Chapter 4.5, Problem 36PE

A respiratory cycle is defined as the beginning of one breath to the beginning of the next breath. The rate of air intake $r$ (in L/sec) during a respiratory cycle for a physically fit male can be approximated by $r\left(t\right)=0.9\sin \frac{\pi }{3.5}t$ , where $t$ is the number of seconds into the cycle. A positive value for $r$ represents inhalation and a negative value represents exhalation.

a. How long is the respiratory cycle?

b. What is the maximum rate of air intake?

c. Graph one cycle of the function. On what interval does inhalation occur? On what interval does exhalation occur?