These are some mathematics investigations I have pursued over the years. They may be of some interest to teachers, students, or hobbyists. I try to convey a conceptual understanding, usually without rigorous proof. Some of the lessons are accompanied by questions and suggestions for extensions.

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Some of the lessons are accompanied by questions and suggestions for extensions.

In my pursuit of a teaching career, I was told to justify the study of each concept by establishing its relevance to the students’ lives. Sorry, but I still have trouble buying into that one. Fortunately, poetry and music are rarely put to that same test. As I glance at the list below, I must concede that it would be difficult to convert any of the lessons into food, shelter, or money. These are things that interested me, and now I understand them better. If there is a reward, it is the fact that every time I do this I get better at figuring things out.

I occasionally get email from people seeking permission to use my work. Feel free to cite, quote, edit, reproduce, or distribute anything on this site. Do not worry about putting my name on it, but please do not put your own name on it.

Many of these presentations use the Geometer’s Sketchpad, but only one of them actually requires it. If you do not have the software, let me suggest that you follow this link to Key Curriculum Press and look into it.

Paul Kunkel

March 16, 2016

Updated the animations on Hanging With Galileo.

October 23, 2015

Updated the animations on Reuleaux Triangle.

October 9, 2015

Updated the animations on the Vernier Scale page of the Geometry of Surveying.

October 8, 2015

NIKE Air gris Max 90 Womens B005OCSI58 Style: Air 325213 Mujeres 325213-048 Lobo gris/ blanco-gris oscuro a49cbefUpdated the animations on Linkages.

October 4, 2015

Updated the animations on On the Square.

September 25, 2015

Updated the animations on Tangent Circles.

September 23, 2015

Updated the lead page of Conic Sections and Construction.

The page it replaced had java animations that were not being treated well by modern browsers. New images were generated with the developmental Web Sketchpad, which is producing very satisfying results. This appears to be the future, so expect more of my pages to be similarly updated soon.

February 26, 2015

Added Book VII to the Conics of Apollonius.

This is the final surviving book of the treatise.

October 22, 2014

Added Book VI to the Conics of Apollonius.

June 10, 2014

Added Book V to the Conics of Apollonius.

Includes GSP-3 files

Includes GSP-4 files

Includes GSP-5 files
Contents:

We are given two fixed points in a vertical plane. A particle starts from rest at one of the points and travels to the other under its own weight. Find the path that the particle must follow in order to reach its destination in the briefest time.

This is a famous problem in the calculus of variations. Nothing new is presented here, but the explanation is more thorough than most.

Buffon’s Needle

An old probability exercise is aided by an interactive Sketchpad file. By manipulating the sketch, an intuitive understanding may be gained, even if the student has had no introduction to calculus.

NIKE Air gris Max 90 Womens B005OCSI58 Style: Air 325213 Mujeres 325213-048 Lobo gris/ blanco-gris oscuro a49cbef

Chinese Handcuffs This has no lesson, only questions. It is just an interesting animated file, which invites student investigation. It has applications for geometry,

Zapatilla para mujer Saucony tipo A8 Blanco | , Zapatillas de montaña de montaña Akyra La Sportiva para mujer Slate / Jadegreen Zapatillas de running NIKE Lunar Skyelux para mujer Negro / Blanco / Antracita Zapato de running ASICS para mujer Torrance Azul humo / Azul humo / Begonia rosa Calzado de running NIKE RN 2017 2017 para mujer Negro / Fuchsia Glow / Hyper Magenta , Zapatillas de running New Balance de mujer Fresh Foam Kaymin v1 Fiji / Coral vivo Under Armour Women s HOVR Sonic NC Grafito / Plata Metálica / Grafito , Zapato de running ASICS Gt-2000 5 para mujer Grey medio / blanco / rosa , Zapatillas de running New Balance 520v3 para mujer Negro Calzado de running New Balance Foam Zante v2 para mujer New Balance Gris / rosa , Calzado de running Kindred para mujer Ryka Gris / rosa , Zapatillas para correr Brooks Cascadia 12 para mujer Peacoat / Flor de la pasión / Bluebird Zapatillas para correr inteligentes para mujer Runtopia Reach 2.0, equipadas con chip de seguimiento de datos Ash Black Zapatillas de running ASICS GT-2000 6 para mujer Indigo Blue / Indigo Blue / Smoke Blue Zapatillas de running NIKE Air Max Flair para hombre Wolf Gray / Cool Grey-black PUMA Men s Roma Basic Sneaker Blanco / Blanco / Goma HOKA ONE ONE Bondi 4 Mujeres Corso azul / coral de neón , Zapatillas de running Mizuno Wave para mujer Inspire 14 Dapple Gray / Clover , Zapatillas para correr Nike Women s Free Rn Flyknit 2017 Hyper Turq / Black-volt-rio , Zapatillas de correr de espuma fresca New Balance 1080v8 para mujer Blanco negro Zapatillas de running ISO para mujeres de la guía Saucony Pizarra / Melocotón , Zapatillas de running adidas Performance Women s Lite Slip-On Marrón / marrón / rosa , Zapatillas de running adidas Ultraboost W para mujer Blanco / blanco / blanco cristal , Zapatillas de running NIKE Zooms Winflo 4 para mujer Ink / Deadly Pink-fire Pink Zapatillas para correr New Balance Rushv3 para mujer Poisonberry / Black Amortiguación 635v2 New Balance para mujer Negro Zapatillas de running NIKE para mujer Lunarepic Low Flyknit 2 Colegio Navy / Black Concord Zapatillas de running Brooks Womens Ghost 10 Neutral acolchadas Pavo real negro / rosa / Living Coral New Balance Women s w990v4 Running Shoe Gray / Castlerock

trigonometry, and probability. Fair warning: The discussion revolves about
a figure that appears only when the sketch is animated. Without Geometer’s
Sketchpad, this one will make little sense at all.
Conic Sections and Construction

My emphasis is on geometric properties of the conic sections, particulary understanding that has been handed down to us in ancient texts. There also are some challenging constructions.

The Geometry of Surveying

This used to be my job, and I enjoyed studying all of the geometrical concepts that were part of the science of land surveying. In this article I discuss the instruments of the profession, their operating principles, their error, and their calibration.

Hanging with Galileo

An investigation into the catenary, the curve formed by a chain suspended at both ends. It also extends into the curve of the main cables on a suspension bridge, which, interestingly, is not a catenary.

Inversion Geometry Calzado de running rápido para mujer Reebok, tejido flexible Colegial azul marino / Laguna azul / Raincloud / Blanco Sandalia de susurro de mujer Keen Sombra Oscura / Cerámica , Sanda Verra Teva para mujer Surf Negro / Multi Zapatillas de senderismo Air Mesh de Ahnu para mujer con malla de aire Gris medio , Zapatillas de correr Mesh Lone Peak 3.5 de Altra para mujer Púrpura / Naranja , Frances Valentine Womens Dizzie Tabaco / blanco Chaco Mujer Zcloud 2 Athletic Sandal Trace Eclipse , Amortiguación 635v2 New Balance para mujer Negro , Zapato San Antonio Mujer SAS, Zapatilla de deporte Freetime con cordones Blanco , Zapatillas para caminar con cordones Go Walk 4 de Skechers Performance para mujer Blanco negro , Zapatillas de deporte vanguardista Speeds Varsity Vanguard para mujer Brooks Riviera / Microchip Gray Sandalias de mujer Merrell Terran Cross II masilla / melocotón Zapatillas de paseo Skechers Go Walk Lite-15433 para mujer gris , Zapatillas de tenis ASICS Gel-Solution Speed 3 para mujer Negro / rosa fuerte / plateado Sandalia Cain Joie para mujer Blanco , Sandalia de cuero Merrell Dwaykair Seaway para mujer Merrell Oak Zapato de voleibol de control de corte de gel femenino ASICS Negro / Plata , Zapatillas de deporte Bloch para mujer, malla Rosado Mocasines casuales Alpargata Deconstructed de TOMS para mujer Oxford Tan Suede Vionic Womens Cosy Juniper Moc Toe Shearling Zapatillas Gris oscuro Zapatillas de carretera Shimano SH-RT5W para mujer marrón Zapato de campo traviesa Kilkenny XC5 para mujer Saucony Lavanda | , Under Armour Fusible para mujer FST Apollo Gray (100) / Glacier Grey , Magic-MC New Summer Zapatillas Cork Slides Pisos con 2018 Nuevas mujeres ocasionales Deslizamiento en toboganes de playa Zapatillas Flip Flops Talla extra Lugar Botas para mujer InterestPrint Botas con cordones con diseño exclusivo Multi 12 , Zapato Oxford de Tompkins de Cole Haan para mujer Patente de color caqui de verano CLARKS Womens Un Cruise Lace (Wave) Sneaker Cuero negro , Gentle Souls de Kenneth Cole Penny Tobillera para mujer Negro Zapato Lites Bates para mujer Blanco , Clásicos de base Slip-on (Tm) para hombres de Vans Tablero de ajedrez negro sin blanco

If you have never studied inversion geometry, you can start here. The elementary concepts are explained. This page is a quick reference for the other lessons that employ inversion geometry.

Linkages

Draw a line segment. Did you use a straightedge? How do you know it was straight?

Java simulations are used to investigate a nineteenth century mechanics problem.

On the Square

The challenge: Given four arbitrary, unique points, *A*, *B*,
*C*, and *D*, construct one line through each point such that the four lines form a square.

Orthocenter What is so significant about the orthocenter of a triangle? Why does it even have a name? This investigation was prepared for a geometry teachers’ workshop. It includes a lesson handout in Word format. This lesson was written for use in a computer lab with the Geometer’s Sketchpad, but with a little editing it should work just as well with Cabri or Cinderella.

The Planimeter

A planimeter is a drafting instrument used to measure area. Its mechanism is quite simple, but understanding why it works is more elusive.

Platonic Solids

Find the inradius, circumradius, dihedral angle, surface area, and volume of all of the Platonic solids. There is also some information about some of their other interesting properties.

Reuleaux Triangle

It is not a circle, but it has constant width. Study the properties of this figure with interactive animated sketches.

Rungs and Vineyards

How is that for a descriptive title? Here are investigations of two interesting visual effects seen from a moving automobile. It includes two interactive perspective drawings, and a discussion of the cylindrical and planar projections used to create them.

The Sliding Triangle

An interesting accidental discovery – Investigate ellipses by tracing triangle transformations.

Table Patterns

Explore geometric patterns formed in a table of modular multiplication. This one requires some elementary knowledge of congruence classes and modular arithmetic.

Tangent Circles

Three circles are given. How many circles can be constructed tangent to all three? How are they constructed? This lesson includes ten animations covering all of the special cases. Some of them are very complex. A little knowledge of circle inversions would help.

Volume of a Torus Do you already know the volume of a torus? Then humor me. I just figured NIKE Air gris Max 90 Womens B005OCSI58 Style: Air 325213 Mujeres 325213-048 Lobo gris/ blanco-gris oscuro a49cbef it out, and I got a chance to try out this new graphics software.

Resources

The Geometer’s Sketchpad Workshop

It is plain to see that I am very fond of Sketchpad. This page was created after the release of version 4. The idea is to have a place to exchange ideas with other users, especially those who are using the advanced features. Here are some custom tools and some information on Java Sketchpad.

Sketchpad Gallery These are some of my best sketches. You may find them useful or interesting by themselves.

Geometry Construction Reference

Thirteen elementary straightedge
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and compass constructions are described and illustrated. The original version,
in Word format, can be downloaded and distributed.

Last update: March 16, 2016 ... Paul Kunkel

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