Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry, Third Edition focuses on the fundamentals: preparation for class, practice with homework, and reviewing of key concepts. With the Concepts Through Functions series, the Sullivans expose students to functions in the first chapter and maintain a continuous theme of functions throughout the text. This approach ensures students master basic skills and develop the conceptual understanding they need for the course, ultimately preparing students for future math courses as well.