Trap a Surprise in an Isosceles Trapezoid
Margaret M. Housinger
	Isosceles trapezoids with integral sides in which a circle can be inscribed.
	(889, 1996)  12 - 14

Perimeters, Patterns, and Pi
Sue Barnes
	Areas and perimeters of inscribed and circumscribed regular polygons.
	(889, 1996)  284 - 288

A Mean Solution to an Old Circle Standard
Andrew J. Samide and Amanda M. Warfield
	A line is tangent to two tangent circles, find the length of the segment joining the 
	two points of tangency.
	(889, 1996)  411 - 413

Geometry in English Wheatfields
	The geometry and diatonic ratios of crop circles.
	(88, 1995)  802

Pi Day
Bruce C. Waldner
	Mathematically related contests held on March 14 (i.e. 3/14).
	(87, 1994)  86 - 87

Investigating Circles and Spirals with a Graphing Calculator
Stuart Moskowitz
	Activities involving parametric equations.
	(87, 1994)  240 - 243

A Rapidly Converging Recursive Approach to Pi
Joseph B. Dence and Thomas P. Dence
	An algorithm for estimating pi from a sequence of inscribed 
	regular polygons.  
	(86, 1993)    121 - 124

A Circle is a Rose
Margaret M. Urban
	Area conjectures for a rose curve.
	(85, 1992)    114 - 115

Circles Revisited
Maurice Burke
	Using three theorems about circles to demonstrate eighteen theorems.
	(85, 1992)    573 - 577

The Circle and Sphere as Great Equalizers
Steven Schwartzman
	Relations between parts of figures and inscribed figures.
	(84, 1991)  666 - 672

A New Look at Circles
Dan Bennett
	A locus problem from Calvin and Hobbes.
	(82, 1989)     90 - 93

Archimedes and Pi
Thomas W. Shilgalis
	Developing Archimedes' recursion formulas.
	(82, 1989)     204 - 206

Not Just Any Three Points
James M. Sconyers
	Sharing Teaching Ideas.  Why must three points be noncollinear in
	order to determine a circle?  
	(82, 1989)     436 - 437

Archimedes' Pi - An Introduction to Iteration
Richard Lotspeich
	Using inscribed n-gons to develop approximations.
	(81, 1988)    208 - 210

Applying the Midpoint Theorem
Richard J. Crouse
	Sharing Teaching Ideas.  A circle which has as a diameter a segment
	with one endpoint on the x-axis and the other endpoint on the y-axis
	must pass through the origin. 
	(81, 1988)    274

Lessons Learned While Approximating Pi
James E. Beamer
	Approximations of pi.  BASIC, FORTRAN, and TI55-II programs provided.
	80, (1987)  154 - 159.

Finding the Area of Regular Polygons
William M. Waters, Jr.
	Finding the ratio of the area of one regular polygon to that of
	another when  they are inscribed in the same circle.
	80, (1987)  278 - 280

Circles and Star Polygons
Clark Kimberling
	BASIC programs for producing the shapes.
	78, (1985)  46 - 51.

A Property of Inversion in Polar Coordinates
James N. Boyd
	A demonstration of the fact that inversion preserves angle size.
	78, (1985)  60 - 61.

An "Ancient/Modern" Proof of Heron's Formula
William Dunham
	Utilizing Heron's inscribed circle and some trigonometric results.
	78, (1985)  258 - 259.

The Shoemaker's Knife - an Approach of the Polya Type
Shlomo Libeskind and Johnny W. Lott
	The arbelos and some circle geometry.  The solution of a given
	problem by looking at a transformed problem.
	77, (1984)  178 - 182.

A Useful Old Theorem
W. Vance Underhill
	Applications of Ptolemy's theorem.
	76, (1983)  98 - 100.

Inversion in a Circle: A Different Kind of Transformation
Martin P. Cohen
	An analytic introduction to inversion.
	76, (1983)  620 - 623.

More Related Geometric Theorems
Joseph V. Roberti
	Theorems related to the result on the lengths of segments formed
	when secants meet outside a circle.
	75, (1982)  564 - 566.

A Present From My Geometry Class
Andy Pauker
	A look at the product of segments of secants of a circle.
	73, (1980)  119 - 120.

Getting The Most Out Of A Circle
Joe Donegan and Jack Pricken
	Polygons determined by six equally spaced points on a circle.
	73, (1980)  355 - 358.

Are Circumscribable Polygons Always Inscribable?
Joseph Shin
	Develops a condition under which they will be.
	73, (1980)  371 - 372.

Writing Equations For Intersecting Circles
Richard J. Hopkinson
	A method for guaranteeing that two circles will meet at points
	having integer coordinates.
	72, (1979)  296 - 298.

A Unification Of Two Famous Theorems From Classical Geometry
Eli Maor
	Looks at the product of the lengths of segments of intersecting
	secants of a circle.
	72, (1979)  363 - 367.

On The Radii Of Inscribed and Escribed Circles Of Right Triangles
David W. Hansen
	Develops relations between these radii and the area of a right triangle.
	72, (1979)  462 - 464.

A Different Look At pi r*r
William D. Jamski
	Dividing a circle into n congruent sectors, then reassembling
	into a "quadrilateral".
	71, (1978)  273 - 274.

The Three Coin Problem: Tangents, Areas and Ratios
Bonnie H. Litwiller and David R. Duncan
	Finding the area of the "triangle" formed by three mutually
	tangent circles.
	69, (1976)  567 - 569.

Discovering A Congruence Theorem: A Project Of A Geometry For Teachers Class
Malcolm Smith
	Demonstrating that corresponding chords of homothetic circles
	are parallel.
	65, (1972)  750 - 751.

Are Circles Similar?
Paul B. Johnson
	Circles in a plane and on a sphere.
	59, (1966)  9 - 13.

The Circle Of Unit Diameter
J. Garfunkel and B. Leeds
	The use of a circle having diameter one in establishing
	geometric results. There is also some trigonometry.
	59, (1966)  124 - 127.

Radii Of The Apollonius Contact Circles
C. N. Mills
	Development of formula for the radii.
	59, (1966)  574 - 576.

How Ptolemy Constructed Trigonometry Tables
Brother T. Brendan
	Contains some geometry of the circle.
	58, (1965)  141 - 149.

A Deceptively Easy Problem
Jack M. Elkin
	Deals with chords of a circle.
	58, (1965)  195 - 199.

Some Remarks Concerning Families Of Circles and Radical Axes
James A. Bradley, Jr.
	Systems of circles determined by two circles.
	57, (1964)  533 - 536.

How To Find The Center Of A Circle
Kardy Tan
	Four constructions.
	56, (1963)  554 - 556.

A Chain Of Circles
Rodney T. Hood
	An application of inversion.
	54, (1961)  134 - 137.

Some Related Theorems On Triangles and Circles
J. D. Wiseman, Jr.
	Medians of isosceles triangles and chords of circles.
	54, (1961)  14 - 16.

The Problem Of Apollonius
N. A. Court
	History, solutions, recent developments.
	54, (1961)  444 - 452.

A Problem With Touching Circles
John Satterly
	Construction of sets of tangent circles.
	53, (1960)  90 - 95.

Lengths Of Chords and Their Distances From The Center
Hale Pickett
	A theorem and a construction.
	50, (1957)  325 - 326.

Teaching The Formula For Circle Area
Jen Jenkins
	A suggested method.
	49, (1956)  548 - 549.

A Model For Visualizing The Formula For The Area Of A Circle
Clarence Olander
	How to construct it.
	48, (1955)  245 - 246.

The Problem Of Napoleon
C. N. Mills
	Finding the center and radius of a circle.
	46, (1953)  344 - 345.

A Circle Device For Demonstrating Facts Which Relate To Inscribed Angles
Emil J. Berger
	Construction and use.
	46, (1953)  579 - 581.

A Teaching Device For Geometry Related To The Circle
M.H. Ahrendt
	A device for working with inscribed polygons.
	45, (1952)  67 - 68.

Relations For Radii Of Circles Associated With The Triangle
Herta Taussig Freitag
	Inradius, circumradius, etc.
	45, (1952)  357 - 360.

Incenter Demonstrator
Emil J. Berger
	Its construction and use.
	44, (1951)  416 - 417.

Escribed Circles
Joseph Nyberg
	Some trigonometric results and geometry of the circle.
	40, (1947)  68 - 70.

Dynamic Geometry
John F. Schact and John J. Kinsella
	The use of triangle and quadrilateral linkages as teaching
	devices. Contains some geometry of the circle.
	40, (1947)  151 - 157.

The Hyperbolic Analogues Of Three Theorems On The Circle
Joseph B. Reynolds
	Deals with the product of segments formed by two intersecting lines
	which meet a circle.
	37, (1944)  301 - 303.

The Principle Of Continuity
Francis P. Hennessey
	Some results on polygons and circles.
	24, (1931)  32 - 40.

Circles Through Notable Points Of The Triangle
Richard Morris
	Circles through three, four, five, and six points. A general theorem.
	21, (1928)  63 - 71.

Original Solution In Plane Geometry
Robert A. Laird
	The points of intersection of external tangents drawn between any
	two three circles of different sizes, in turn, lie on a straight line.
	15, (1922)  361 - 364.

Inscribing Regular Pentagons and Decagons
Joseph Bowden
	Analytic proof of the construction proposed.
	8, (1915-1916)  89 - 91.

Approximate Values Of pi
Wilfred H. Sherk
	Six approaches.
	2, (1909-1910)  87 - 930

H.J.L.
07/15/97
email:  00hjludwig@bsu.edu
home page: http://www.cs.bsu.edu/~hjludwig/