Electronic Proceedings of the Eleventh Annual Conference on Technology in Collegiate Mathematics


The Magic Calculator and The Sine Addition Formula

Bryan Dorner
Mathematics Department
Pacific Lutheran University
Tacoma, WA 98447
Phone: (253) 535-8737
E-mail: dornerbc@plu.edu


This paper describes how beginning trigonometry students can compute the sine and cosine of any angle to any degree of accuracy using only simple geometry and a calculator with a square root key. The ideas in this algorithm also provide a simple derivation of the angle addition identity: sin(x+h)=sin(x)cos(h)+cos(x)sin(h).