396 MATHEMATICS MAGAZINE REFERENCES 1. Girolamo Cardano, De Subtilitate libri XXI, 1550. 2. Whitfield Diffie and Martin E. Hellman, New Directions in Cryptography, IEEE Transactions on Information Theory, Vol. IT-22 (November 1976), pp. 29–40. 3. Martin Gardner, Codes, Ciphers and Secret Writing, Dover Publications, Inc., New York, 1972. 4. Charlie Kaufman, Radia Perlman, and Mike Speciner, Network Security: PRIVATE Communication in a PUB- LIC World, Prentice Hall, 1995. 5. Rudolf Kippenhahn, Code Breaking: A History and Exploration (English version translated from German), Overlook Press, Woodstock, N.Y., 1999. 6. National Institute of Standards and Technology (NIST), Digital Signal Standard, Federal Information Process- ing Standards (FIPS) Publication 186-2, 2000. 7. Bruce Schneier, Applied Cryptography (2nd Edition), John Wiley & Sons, Inc., 1996. 8. Simon Singh, The Code Book, Doubleday, 1999. Math Bite: Axial View of Trigonometric Functions M. VALI SIADAT Richard J. Daley College Chicago, IL 60652 A typical way to picture the sine and cosine functions is shown in FIGURE 1, where a given central angle θ appears in its standard position in the unit circle of the Cartesian plane. Since the horizontal distance OM is cos θ, we may loosely call the horizontal axis the cosine axis. Similarly, the vertical distance OL is sin θ and so the the sine function is associated with the vertical axis. An advantage of this approach is that students can reliably determine the correct signs for these ratios when θ is outside the first quadrant. You may be familiar with similar axes associated with the tangent and cotangent functions, but have you ever thought of a secant axis? Figure 1 An angle in standard position in the first quadrant