University of Wisconsin: H. Jerome Keisler's "Elementary Calculus, Chapter 8: Exponential and Logarithmic Functions, Section 8.4: Some Uses of Exponential Functions"
Read Section 8.4 (pages 449 through 453). In this chapter, you will learn the definitions of the hyperbolic trig functions and how to differentiate and integrate them. The chapter also introduces the concept of capital accumulation.