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

New Orleans, Louisiana, November 19-22, 1998

Paper C026

The Magic Calculator and The Sine Addition Formula

Bryan Dorner

Mathematics Department
Pacific Lutheran University
Tacoma, WA 98447
Phone: (253) 535-8737

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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).

Keyword(s): trigonometry, TI-82