Our editor, Jerry Porter, has observed that calculating the angle between radius and tangent by using the dot product is a nice linear algebra problem. That could also be done in a multivariable calculus course, where dot product is a standard topic. We have not included this in the module because our students do this module before any vectors appear in the calculus course, and few if any have taken or are taking a linear algebra course. However, this would make a nice follow-up homework or test problem once the dot product has been introduced. (Authorsâ€™ preface)