CHAPTER 5 - TRIGONOMETRY: THE CIRCULAR FUNCTIONS

Abstract

This chapter discusses the concepts of trigonometry. The modern approach is to deal with trigonometry in terms of functional relationships. The trigonometric functions can be viewed as functions whose domains are angles or as functions whose domains are real numbers, in which case they are referred to as the circular functions. The chapter presents the latter approach as it more clearly demonstrates the utility of the function concept. There are six trigonometric or circular functions that are defined by the wrapping function. These include sine, cosine, and tangent functions, which are written as sin, cos, and tan, respectively. The remaining three functions are reciprocals of these, which include secant, cosecant, and cotangent, which are written as sec, cosec, and cotan. The chapter also discusses the properties of the circular functions and identities of trigonometry, that is, equations that are true for all values in the domain of the variable. Identities are useful in simplifying equations and in providing alternative forms for computations.