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AMATYC Review Fall 2008
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The AMATYC Review

A refereed publication of the American Mathematical Association
of Two-Year Colleges

Editor: Barbara S. Rives, Lamar State College

Production Manager: John C. Peterson


Fall 2008 issue, Vol. 30, No.1

Table of Contents

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From the Editor's Keyboard

Greetings! It hardly seems possible another semester is underway and the fall AMATYC conference in Washington, DC will be here. Time passes quickly and my five-year commitment as editor ends at the conclusion of the fall 2008 conference in Washington, DC. This column is the last "From the President's Keyboard" column written by your current editor. The five years have been interesting, challenging, enlightening, and rewarding. Each issue of The AMATYC Review involved the contributions of many people and a special "thank you" goes to each of the following:

  • Production Manager: John Peterson, whose experience and expertise prepared the journal for publication by typesetting articles, designing many of the journal covers, making changes to the proofs, and completing a multitude of other items needed to finalize the journal for publication.
  • AMATYC Board liaisons: Wanda Long, Irene Doo, and Jane Tanner who provided guidance, proofreading, and help whenever needed.
  • The AMATYC office staff: Cheryl Cleaves, Beverly Vance, and Christine Shott who answered many questions, provided guidance, and resources.
  • Authors: Without your contributions, The AMATYC Review would not have been possible. Thank for your patience during the review process.
  • Reviewers and Editorial panelists: See pages ?? and ?? for the names of these contributors to The AMATYC Review. They contributed their time and expertise to reviewing articles and making recommendations to the editor.
  • Feature editors: Brian Smith (software review editor), Sandra DeLozier Coleman (book review editor), and Stephen Plett (problems section editor). A special thanks to the late Robert Stong who died in April (see page ??). He served as the solutions editor for the problems section of The AMATYC Review for 20 years.
  • University and college support: Abilene Christian University, Abilene, TX and Lamar State College-Orange, Orange, TX for their administrative support of the editor by providing space for the AMATYC editorial materials, released time for AMATYC work, and general encouragement and office materials.
  • AMATYC Presidents: Judy Ackerman, Kathy Mowers, and Rikki Blair for their guidance, support, and vision for AMATYC.

One of the most frustrating aspects of being editor was not being able to publish all the excellent articles that could have been published - if space had been available. These manuscripts were forwarded to the AMATYC office in Memphis in anticipation of the selection of the new editor and production manager.

Best wishes to the new editor and production manager as they take responsibility for developing and producing the journal. A wonderful adventure awaits them. I look forward to receiving the future publications.

Barbara S. Rives, Editor

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Areas and Volumes in Pre-Calculus
Joscelyn A. Jarrett

Joscelyn A. Jarrett is a professor of mathematics at Gordon College in Barnesville, GA. He received his BA (Hons) in mathematics from Fourah Bay College in 1967, an MS in mathematics from the University of Toronto in 1970 and a PhD in secondary mathematics education from the University of Iowa in 1980. Joscelyn is an active member of both the National Council of Teachers of Mathematics and the American Mathematical Association of Two-Year Colleges.

This article suggests the introduction of the concepts of areas bounded by plane curves and the volumes of solids of revolution in Pre-calculus. It builds on the basic knowledge that students bring to a pre-calculus class, derives a few more formulas, and gives examples of some problems on plane areas and the volumes of solids of revolution that could be solved at the pre-calculus level. More students will benefit from the exposure to these concepts, as not all pre-calculus students go on to take calculus. Furthermore, when students do get to calculus, they would have already acquired some skills in visualizing mental images or drawing sketches of solids of revolution.

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The Mathematics of Starry Nights
Farshad Barman

Farshad Barman received his PhD in electrical engineering from the University of California in Santa Barbara in 1979. He taught and worked in that eld until 1992. He received his master's degree in mathematics from Portland State University in 1995 and has been teaching mathematics at Portland Community College since then. His current interests are the mathematics of astronomy, stargazing, and baseball.

The mathematics for finding and plotting the locations of stars and constellations are available in many books on astronomy, but the steps involve mystifying and fragmented equations, calculations, and terminology. This paper will introduce an entirely new unified and cohesive technique that is easy to understand by mathematicians, and simple enough to fit on one line, and easy to program into a graphing calculator. The result will be a 2 xn matrix of star coordinates that will model the positions of naked-eye visible stars and constellations for a given date and time and location of the observer. This technique is based on coordinate transformations in and mapping from to . The precession of the equinoxes will be explained and included in the calculations, and will therefore make the star plots accurate for approximately two thousand years into the future or the past. This paper provides examples for the application of linear transformations and mappings, using one of the most natural physical phenomena, and is written for readers with limited knowledge of astronomy.

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The Principal Square Root of Complex Numbers
Terence Brenner
It is stated in any algebra book that the principal square root of a positive number is . In this article, the definition of the principal square root is expanded to include complex numbers.

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On the Presentation of Pre-Calculus and Calculus Topics: An Alternate View
Aleksandr Davydov and Rachel Sturm-Beiss

Aleksandr Davydov is an assistant professor of mathematics at the Kingsborough Community College (KCC) of the City University of New York (CUNY). He earned his MS in mathematics from Samarkand State University (Russia) and his PhD in mathematics from Ural State University (Russia). His primary area of interest is differential equations and their applications.

Rachel Sturm-Beiss is an associate professor of mathematics in Kingsborough Community College (KCC) of the City University of New York (CUNY). She earned her PhD in pure mathematics from the Courant Institute of New York University. Her primary area of interest is statistical processes and modeling.

The orders of presentation of pre-calculus and calculus topics, and the notation used, deserve careful study as they affect clarity and ultimately students' level of understanding. We introduce an alternate approach to some of the topics included in this sequence. The suggested alternative is based on years of teaching in colleges within and outside the US, and on our careful review of textbooks currently used in two-year and four-year colleges.

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How to Design Your Own to e Converter
Harlan J. Brothers

Harlan Brothers is Director of Technology at The Country School in Madison, CT where he teaches programming, fractal geometry, and guitar. Having worked for six years with Michael Frame and Benoit Mandelbrot at the Yale Fractal Geometry Workshops, he now lectures on the subject of fractal music. Harlan is also an inventor with five US patents.

A simple restatement of its limit definition formula allows one to derive trigonometric approximations for e. These novel closed-form expressions can then be used as functions that will "convert" the digits of into those of e. Maclaurin series expansions are used to assess rates of convergence for these expressions.

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Meet Me at the Crossroads: Over-Fishing to Meet the Standards
John E. Donovan, II

John teaches mathematics and mathematics education at the University of Maine. In addition to developing and discovering practical applications of math, he enjoys fly shing in the Penobscot River from his kayak, spending time with his wife and 4 kids, all things Mac, and long walks listening to novels on his iPod.

To achieve the vision of mathematics set forth in Crossroads (AMATYC, 1995), students must experience mathematics as a sensemaking endeavor that informs their world. Embedding the study of mathematics into the real world is a challenge, particularly because it was not the way that many of us learned mathematics in the first place. This article is about one such example, the effects of fishing on fish populations, but the method of analysis used is widely applicable. The fishing model developed is based on intuitions about how populations change over time. Traditionally such examples are reserved for the study of calculus and differential equations, but qualitative methods of analysis make them accessible to students in precalculus. This example, and others like it, should not be considered add-ons to an already over-burdened curriculum. Rather, such problems provide launching points for students to develop deep understandings of mathematics through investigation of things that are real.

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Successful Developmental Mathematics Education: Programs and Students - Part III
Irene M. Duranczyk

Irene is an assistant professor in the Department of Postsecondary Teaching and Learning with an EdD from Grambling State University, Louisiana. She taught developmental mathematics since 1990 and was an administrator of developmental programs for over 20 years. Irene is the recipient of the 2007 National Association for Developmental Education's (NADE) Outstanding Research Conducted by a Developmental Education Practitioner Award.

This is the third and final article in this series. The first article reviewed the literature for research studies on successful developmental programs and students. The second article reported on the qualitative research methods and results documented from a purposive sample of twenty successful developmental mathematics students 3-5 years after completing their developmental studies. This article presents more detail on what shaped this qualitative study, identifies specific implications for developmental mathematics educators, and makes recommendations for further research on success in developmental mathematics.

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On Moving a Couch Around a Corner
Jawad Sadek and Russell Euler

Russell Euler is a professor in the Department of Mathematics and Statistics at Northwest Missouri State University where he has taught since 1982. His mathematical interests include analysis, differential equations, geometry and number theory. Presently he is the Problem Editor for the Fibonacci Quarterly. Russell enjoys construction, volunteer work at his church, and learning from his three daughters.

Jawad Sadek is a professor in the Department of Mathematics and Statistics at Northwest Missouri State University. His main mathematical interest is complex analysis. Jawad enjoys soccer and traveling around the world.

Finding the longest rectangular couch with a given width that can be maneuvered around a corner is an old and interesting problem. It has been the subject of numerous research articles. In this note, two open questions that were raised in Moretti's article (2002) about the subject are discussed. In addition, the maximum area of a couch rounding a corner is also found.


Moretti, C. (2002). Moving a couch around a corner. The Coll. Math. Journal, 33(3), 196-200.

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Collinear Points Problem
Harris S. Shultz and Ray C. Shiflett
Harris S. Shultz received the Southern California Section of the Mathematical Association of America's Award for Distinguished College or University Teaching in 1992. He has directed numerous institutes for secondary mathematics teachers, has designed online professional development programs and has been a frequent contributor to The AMATYC Review.

Ray C. Shiflett received his PhD at Oregon State University. He has published in operator, measure, matrix, and number theory, topology, optometry, science fiction, and mathematics education. He served as Chair of Mathematics at Wells College, Dean of the College of Science at Cal Poly Pomona, and Executive Director of the National Research Council's Mathematical Sciences Education Board. He enjoys golf, fly fishing, writing songs, and wood working.

Students were asked to find all possible values for A so that the points (1, 2), (5, A), and (A, 7) lie on a straight line. This problem suggests a generalization: Given (x, y), find all values of A so that the points (x, y), (5, A), and (A, 7) lie on a straight line. We find that this question about linear equations must be resolved using the more advanced tools of quadratic equations. The number of possible values of A can be zero, one or two, depending upon the given point (x, y). Moreover, the three cases are partitioned by an oblique parabola having its axis at an angle of 45 degrees to the Cartesian plane coordinate axes.

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Sighting the International Space Station
Donald Teets

Donald Teets has taught at the South Dakota School of Mines and Technology since obtaining his doctorate from Idaho State University in 1988. He received the Allendoerfer award from the Mathematical Association of America in 2000 for an article on the astronomical work of Gauss, and the Distinguished Teaching Award from the Rocky Mountain Section of the MAA in 2004.

This article shows how to use six parameters describing the International Space Station's orbit to predict when and in what part of the sky observers can look for the station as it passes over their location. The method requires only a good background in trigonometry and some familiarity with elementary vector and matrix operations. An included set of exercises leads the reader step-by-step through the computations. Specific instructions are included for implementation of the method using a spreadsheet tool such as Excel. This article gives students the rare opportunity to use classroom mathematics to solve a complicated real-world problem, and to observe the results of their solution in real time.

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A Binary Divisibility Theorem For Mersenne Numbers
Travis Thompson

Travis Thompson received the PhD degree in mathematics from the University of Arkansas in 1977. He is currently the dean of the college of sciences at Harding University in Searcy, Arkansas.

Arithmetic tests for divisibility of an integer by another integer are well known. This article states and proves conditions for divisibility in binary form.

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Book Review
Edited by Sandra DeLozier Coleman
YEARNING FOR THE IMPOSSIBLE - The Surprising Truths of Mathematics, John Stillwell. A.K. Peters, Ltd., Wellesley, Massachusetts, 2006. Hardcover. xiii + 244 pp. ISBN 978-1-56881-254-0.

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The Problems Section
Edited by Stephen Plett and Robert Stong

New Problems

The BA Problem Set consists of four new problems.

Set AY Solutions

Solutions are given to the five problems from the AY Problem Set from the Fall 2007 issue of The AMATYC Review. In addition, addenda were provided for the solvers of the AW Problem Set from the Fall 2006 issue.

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