Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry, Second Edition embodies Sullivan/Sullivan's hallmarks–accuracy, precision, depth, strong student support, and abundant exercises–while exposing readers to functions in the first chapter. To ensure that students master basic skills and develop the conceptual understanding they need for the course, this text focuses on the fundamentals: preparing for class, practicing their homework, and reviewing the concepts. After using this book, students will have a solid understanding of algebra and functions so that they are prepared for subsequent courses, such as finite mathematics, business mathematics, and engineering calculus.