Precalculus: An Investigation of Functions is a free, open textbook covering a twoquarter precalculus sequence including trigonometry. The first portion of the book is an investigation of functions, exploring the graphical behavior of, interpretation of, and solutions to problems involving linear, polynomial, rational, exponential, and logarithmic functions. An emphasis is placed on modeling and interpretation, as well as the important characteristics needed in calculus.
The second portion of the book introduces trigonometry. Trig is introduced through an integrated circle/triangle approach. Identities are introduced in the first chapter, and revisited throughout. Likewise, solving is introduced in the second chapter and revisted more extensively in the third chapter. As with the first part of the book, an emphasis is placed on motivating the concepts and on modeling and interpretation.
In addition to the paper homework sets, algorithmetically generated online homework is available as part of a complete course shell package, which also includes a sample syllabus, teacher notes with lecture examples, sample quizzes and exams, printable classwork sheets and handouts, and chapter review problems. If you teach in Washington State, you can find the course shell in the WAMAP.org template course list. For those located elsewhere, you can access the course shell at MyOpenMath.com. A selfstudy version of the online course exercises is also available on MyOpenMath.com for students wanting to learn the material on their own, or who need a refresher.
The whole book or individual chapters are available for download below, or you can order a bound printed copy from CreateSpace.com or Lulu.com. If you are providing a link to students or a bookstore to purchase printed copies of the book, please direct them to this page. If you are an instructor and are using this book with your class, please drop us an email so we can track use and keep you updated with changes.
Errata (errors in the 1st edition). Many of these errors have been corrected in Edition 1.5.
Note: On July 3, 2015, Edition 1.5 was released. The links below point to this, the most current version. This edition is page number and problem set number equivalent to Edition 1.0  1.4; it features error and typo corrections.
Contents  Traditional Book  Detailed Solutions 

Whole Book  PDF Order from CreateSpace Order from Lulu Order from Amazon 

Front Matter  PDF DOC  PDF DOC 
Chapter 1: Functions

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Chapter 2: Linear Functions

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Chapter 3: Polynomial and Rational Functions

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Chapter 4: Exponential and Logarithmic Functions

PDF DOC  PDF DOC 
Chapter 5: Trigonometric Functions of Angles

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Chapter 6: Periodic Functions

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Chapter 7: Trigonometric Equations and Identities

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Chapter 8: Further Applications of Trigonometry

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Answers to Selected Exercises  PDF DOC  
Index  PDF DOC  
Alternate Extended Chapter 3: Polynomial and Rational Functions
This chapter is not included in the standard print version. There is a full book PDF including the extended chapter, and it is available in print via Lulu. 
PDF DOC 
Text last updated: July 3, 2015. Solutions updated: April 20, 2015
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The detailed solutions manual was contributed by Shoreline Community College and Evergreen State College, and is licensed under a Creative Commons AttributionNonCommercial ShareAlike License.
Note: The "Split book" version of the book has been phased out due to lack of interest.
Note on versions: The links above will redirect you to the latest edition of the chapters. Older versions remain on the website, and can be accessed using direct links to the specific edition's file name, like http://www.opentextbookstore.com/precalc/1.0/Chapter 1.pdf