This textbook is the third year in an Algebra 1 - Geometry - Algebra 2 series. As in the first two years, the program is organized around interesting, complex problems, and the concepts you learn grow out of what you'll need to solve those problems. This book contains the tasks that will be your work during this third year of the program. As you will see, these problems require ideas from many branches of mathematics, including algebra, probability, graphing, statistics, and trigonometry. Rather than present each of these areas separately, we have often integrated them and presented them in meaningful contexts, so you will see how they relate to each other and to our world. Each unit in this program has a central problem or theme and focuses on several major mathematical ideas. Supplemental problems at the end of the main material for each unit provide additional opportunities for you to strengthen your understanding of the core material or to explore new ideas related to the unit. -- Note to students.