There are many many useful online math resources. For your hassle-free search all maths formulas PDF is available at a single-desk. Mathematical Methods in the Physical Sciences by Boas.
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Former Professor and Chairman of Mathematics Rensselaer Polytechnic Institute Hartford Graduate Center Schaums Outline Series New York Chicago San Francisco Lisbon. One of the simplest and most basic formulas in Trigonometry provides the measure of an arc in terms of the radius of the circle N and the arcs. However you can print every page to pdf to keep on you computer or download pdf copy of the whole textbook. John Wiley Publ About the right level and with a very useful selection of topics.