Students use the Law of Cosines and tools of construction, the quadratic formula, and graphing parabolas to explore the ambiguous case of the Law of Sines. (Author/NB)

By selecting certain special triangles, students can learn about the laws of sines and cosines without wrestling with long decimal representations or irrational numbers. Since the law of cosines requires only one of the three angles of a triangle, there are many examples of triangles with integral sides and a cosine that can be represented exactly…

This article describes an alternate way to utilize a circular model to represent thirds by incorporating areas of circular segments, trigonometric functions, and geometric transformations. This method is appropriate for students studying geometry and trigonometry at the high shool level. This task provides valuable learning experiences that…

This paper takes a known point from Brocard geometry, a known result from the geometry of the equilateral triangle, and bring in Euler's [empty set] function. It then demonstrates how to obtain new Brocard Geometric number theory results from them. Furthermore, this paper aims to determine a [triangle]ABC whose Crelle-Brocard Point [omega]…

This textbook presents principles, ratios and proportions, the circle and measurement of angles, regular polygons and measurement of the circle, planes and solid angles, polyhedrons, the three round bodies, plane and spherical trigonometry, and mensuration. [This book was translated by David Brewster. It was revised and adapted by Charles Davies.]

This textbook presents principles, ratios and proportions, the circle and measurement of angles, regular polygons and measurement of the circle, planes and solid angles, polyhedrons, the three round bodies, plane and spherical trigonometry, and mensuration. [This book was translated by David Brewster. It was revised and adapted by Charles Davies.]

In this article, the author offers two well-known mathematical images--that of a dot moving around a circle; and that of the tens chart--and considers their power for developing mathematical thinking. In his opinion, these images each contain the essence of a particular topic of mathematics. They are contrasting images in the sense that they deal…

In light of evidence indicating that errors in making accurate pie charts are prevalent, an alternative method for constructing pie charts is proposed. It involves the use of a simple trigonometric formula to compute a factor of the length of the chord that defines a given percentage sector. This factor is multiplied by the radius of the circle to…

This investigation extends a 25-point geometric system for defining a 25-point trigonometry whose properties are analogous to those of the trigonometry of the Euclidean plane. These properties include definitions of trigonometric functions arising from ratios of sides of right triangles, the relations of elements of a given triangle through the…

This textbook discusses ratios and proportions; the circle and measurement of angles; proportions of figures--measurement of areas; regular polygons--measurement of the circle; planes and polyhedral angles; polyhedrons; the cylinder, cone, and sphere; spherical geometry; plane trigonometry; analytical trigonometry; spherical trigonometry; and…

This textbook presents principles, ratios and proportions, the circle and measurement of angles, regular polygons and measurement of the circle, planes and solid angles, polyhedrons, the three round bodies, analytical trigonometry, plane and spherical trigonometry, and mensuration. [This book was revised and adapted by Charles Davies.]

This textbook presents principles, ratios and proportions, the circle and measurement of angles, regular polygons and measurement of the circle, planes and solid angles, polyhedrons, the three round bodies, analytical trigonometry, plane and spherical trigonometry, and mensuration. [This book was revised and adapted by Charles Davies.]

This textbook presents principles, ratios and proportions, the circle and measurement of angles, regular polygons and measurement of the circle, planes and solid angles, polyhedrons, the three round bodies, analytical trigonometry, plane and spherical trigonometry, and mensuration. [This book was revised and adapted by Charles Davies.]