This is volume 4, book 5 of Teaching True Mathematics, designed for College Sophomore-year students, students of age 19-20. It is the continuation of volume 3 in the end-goal of learning how to do the mathematics of electricity and magnetism, because everything in physics is nothing but atoms and atoms are nothing but electricity and magnetism. To know math, you have to know physics. We learned the Calculus of 2nd dimension and applied it to the equations of physics for electricity and magnetism. But we did not learn the calculus of those equations for 3rd dimension. So, you can say that Sophomore year College math is devoted to 3D Calculus. This sophomore year college we fill in all the calculus, and we start over on all of Geometry, for geometry needs a modern day revision. And pardon me for this book is mostly reading, and the students doing less calculations. The classroom of this textbook has the teacher go through page by page to get the students comprehending and understanding of what is being taught. There are many hands on experiments also.