xplores a variety of fun and informative topics in trigonometry, from basics like defining the sine and cosine functions, to less frequently seen topics like Lissajous curves and different ways of deriving the value of pi. These topics are introduced through conversations between the characters from the Math Girls series, offering a fun way to learn this serious content. Each chapter comes with review problems and answers, and an appendix gives more challenging, open-ended problems for readers wanting to push the limits of their understanding. This book is the third in a series aimed at preparing students for advanced mathematics studies.