A visual proof that sin x/x is monotonically increasing on (0, pi/2). For tan x/x, see p. 420 (EJ1017686).

A visual proof that tan x/x is monotonically increasing on (0, pi/2). For sin x/x, see p. 408 (EJ1017684).

Seasonality analyses are important in medical research. If the incidence of a disease shows a seasonal pattern, then an environmental factor must be considered in its etiology. We discuss a method for the simultaneous analysis of seasonal variation in multiple groups. The nuts and bolts are explained using simple trigonometry, an elementary…

A visual proof that the sine is subadditive on [0, pi].

Using a simple trigonometric limit, we provide an intuitive geometric proof of the Singular Value Decomposition of an arbitrary matrix.

We illustrate and discuss the method, called CORDIC, which many hand calculators use to calculate the trigonometric and other functions.

Given that the sine and cosine functions of a real variable can be interpreted as the coordinates of points on the unit circle, the author of this article asks whether there is something similar for complex variables, and shows that indeed there is.

Computer graphics are used to display the sum of the first few terms of the series solution for the problem of the vibrating string frequently discussed in introductory courses on differential equations. (MNS)

Presented are five short articles which describe innovations in mathematics teaching. Included are "Polar Summation,""The Age of the Solar System,""Forward Homework--A Motivational Tool,""Trigonometric Identities through Calculus," and "Algorithms for Evaluation of Polynomials." (CW)

Discusses whether a map can be constructed using only the distances between 15 selected cities. Concepts used in the discussion come from geometry, matrix theory and trigonometry. (PK)

Contains an update of an earlier listing of software for mathematics instruction at the college level. Topics are: advanced mathematics, algebra, calculus, differential equations, discrete mathematics, equation solving, general mathematics, geometry, linear and matrix algebra, logic, statistics and probability, and trigonometry. (PK)

Argues that while microcomputer and graphing calculators have evolved to a stage where they should be used routinely by mathematics students at all levels, there is sometimes potential to mislead students with computer generated graphs. Examples are included. (PK)

This article, which is organized around a single, well-known algorithm for root extraction, presents a way of incorporating dynamical systems into the teaching of mathematics. Included are sample exercises using complex numbers and the computer where students have the opportunity to do some analysis on this algorithm. (KR)

Presented are six short articles on an application of an ellipse to carpentry, the area of an ellipse by stacking, using the isoperimetric quotient to solve a minimum problem, using an ill-posed trigonometry problem to encourage deeper exploration of concepts, the volume and centroid of the Step Pyramid of Zoser, and a unique telescoping series…

Reviews for three software packages are given. The packages are: Super Math Package, a collection of 19 programs on a variety of mathematical topics; Interactive Experiments in Calculus; and Introductory Statistics Software Package. (PK)