### Home > PC3 > Chapter 8 > Lesson 8.3.3 > Problem 8-124

When a person is breathing normally, the amount of air in their lungs can be modeled with a sinusoidal function. When full, Karen’s lungs hold seconds Karen has exhaled completely and at

*seconds she has completely inhaled.*

Write an equation to model the amount of air in Karen’s lungs at any time

in seconds, assuming she is breathing normally.Make a sketch. Include a minimum point at

and a maximum point at . amplitude:

period:

horizontal shift:using sine

vertical shift:What is the amount of air in Karen’s lungs if she starts holding her breath,

seconds into the timing? Let

in your equation from part (a).When is the first time Karen has

liters of air in her lungs? Set your equation from part (a) equal to

and solve for .