"Precalculus: An Investigation of Functions" is a trade paperback textbook published by Tangential Projects Press in 2022. Written by Melonie Rasmussen and David Lippman, this textbook focuses on the subject areas of education and mathematics, specifically exploring functions in a precalculus context. The book is designed for English-speaking readers and provides a comprehensive investigation into the world of functions, making it a valuable resource for students and educators alike.