Free Precalculus Textbooks
Just as the name implies, precalculus is designed to prepare students moving on from basic mathematics to more complex math concepts. Precalculus textbooks typically build upon earlier courses in algebra and geometry and introduce trigonometry and calculus. Students will work with sets, functions, matrices, vectors and a number of other topics. Prerequisites are two years of algebra and a year of geometry.
High schools and universities offer precalculus courses though at the college level they are sometimes called college algebra or trigonometry. The free online precalculus textbooks that I have found were written for students at all levels. If you are having trouble, you might want to see if one or more of these textbooks are written in such a way that you can understand the material better.
List of Free Precalculus Textbooks
Written by: Dr. Carl Stitz (Lakeland Community College) Dr. Jeff Zeager (Lorain County Community College)
Free college algebra textbook written by two Ohio educators. A truly living text supported by a forum where students are encouraged to ask questions.
Written by: Dr. Carl Stitz (Lakeland Community College) and Dr. Jeff Zeager (Lorain County Community College)
Free precalculus textbook from a pair of true educators. The authors have an open forum and appear happy to answer questions from students and educators.
Written by: Dr. Thomas W. Hungerford (Cleveland Collaborative for Mathematics Education), Irene Jovell (Niskayuna High School) & Betty Mayberry (Pope John Paul II High School)
A high school in Texas has shared a free precalculus textbook for the use of their students and anyone else with an active Google account.
Written by: David H. Collingwood and K. David Prince of the University of Washington
Precalculus, a textbook written by two calculus professors hoping to better prepare their students for the rigors of calculus courses.
Written by: David Lippman and Melonie Rasmussen, faculty at Pierce College
Precalculus textbook which embraces the open textbook initiatives and works with real world examples like age, height, gas prices and even taxi fares.
Written by: Michael Corral (Schoolcraft College)
Free online trigonometry textbook by Michael Corral from Schoolcraft College. Geometrical rather than analysis approach, focus on preparation for later math courses.
Written by: Ted Sundstrom and Steven Schlicker (Grand Valley State University)
Free online trigonometry text that starts with a circular function approach to trigonometry and moves on to the study of triangle trigonometry, vectors, trigonomic identities, and complex numbers.