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

EN/ Zapatilla 19823 Cloudster para mujer Magenta Cloudster/ Berry f07da42Updated 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.

EN/ Zapatilla 19823 Cloudster para mujer Magenta Cloudster/ Berry f07da42

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

Zapatillas de running ASICS Gel-Contend 4 para mujer Negro / Negro / Carbono Zapatillas de running NIKE Lunarglide 9 para mujer Gunsmoke / Solar Red / Hot Punch / Vast Grey Zapatillas de running Pureboost X de adidas Performance para mujer Negro / Negro / Gris Sólido Skechers Performance Women s Go Run 400 Obstruct Negro , Zapato deportivo para acolchado 680v5 New Balance para mujer Coral Zapatillas de running Mizuno Women s Wave Horizon 2 Rosa Glo / Blanco Zapatillas de running NIKE Lunar Skyelux para mujer Aluminio / Binario Azul / Azul Mediano Zapato de running ASICS Alpine XT para mujer Gris Pizarra / Gris Pizarra Zapatillas para correr Nike Women s Free Rn Flyknit 2017 Tierra púrpura / negro , Zapatillas de running NIKE Zoom para mujer Winflo 3 Blanco / Hyper Turquesa / Negro Zapatillas de running ASICS Gel-Cumulus 19 para hombre Negro / Carbono / Rojo Zapatillas de running Mizuno Women s Wave Catalyst 2 Diva Blue / Green Flash Calzado de running NIKE RN 2017 2017 para mujer Azul Zapatillas de running Mizuno Wave para mujer Inspire 13 Malibu Azul / Rosa , Zapatillas de running acolchadas 420v4 para mujer New Balance Silver Mink Zapatillas de running Fresh Life Arishi V1 para mujer New Balance Estratos WMNS Zoom Fly Negro / Blanco-antracita-lobo Gris Zapatillas de running mujer HOKA ONE ONE Clifton 4 Aquifer / Vintage Indigo , Zapatillas de running ASICS GT-2000 6 para mujer Gris medio / plata / carbono Zapatillas de running NIKE Mens Air Zoom Structure 19 Negro / Volt / Blue Lagoon / Blanco , Zapatillas NIKE Air Max 90 Ultra 2.0 Flyknit para mujer White Dark Raisin 102 Zapatillas de running AMPLICA para mujer ASICS Azul índigo / Azul índigo / Coral destello Zapato para correr Saucony Women s Cohesion 9 Plata / azul marino / verde azulado Zapatillas de running ISO para mujeres de la guía Saucony Pizarra / Melocotón Zapatillas de running adidas Originals Women s Tubular Dawn Originals Trace Cargo , Zapatillas adidas Ultraboost X All Terrain LTD Shoe para mujer Negro Zapatillas de running NIKE Women s Air Max 1 Ultra Essentials Blanqueado Lila / Rosa Blast-white Calzado de running Filaity Memory Finity de Fila Negro, blanco, plata metalizado Zapatillas de running Brooks Womens Glycerin 15 Neutral Max Cushion Negro / rosa pavo real / ciruela Caspia

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 Zapatillas de running adidas Mana Bounce 2 W Aramis para mujer Blanco / Metálico / Plateado / Negro Zapatillas de deporte casual Gazelle de adidas para hombre Powred / White / Goldmt Zapatillas de running NIKE Air Zoom Vomero 12 para hombre Azul profundo / Cumbre Blanco-Negro Sirena de mujer Merrell Flip Q2 Athletic Sandal Turquesa , Zapatillas de running Spira Phoenix para mujer con resortes Carbón / Negro / Tsai Rojo Zapatillas de running NIKE para mujer Lunarepic Low Flyknit 2 Platino Blanco / Blanco-puro , Chaco Zcloud 2 Sport Sandal para hombre Seam Rust Altra Women s Provision 2.5 Running Shoe Pavo real / plata , Zapatillas de running ST-2 para mujer Topo Athletic Frambuesa negro , Astral Mary Jay - Mujeres Negro SOREL Womens Ella Lace-Up Natural , Bomba Nikole para mujer Via Spiga Blush Suede , Sandalia Uneek-W de mujer KEEN Midnight Navy / Cendre Blue , Zapatillas de entrenamiento cruzado PUMA para mujer Fierce Core Atolón de cantera azul Zapatillas de entrenamiento cruzado Vibram para mujer V-Train Gold s Gym Negro / Gris / Azul Reflejo , Supra Method Skate Shoe Cool Gray / Black-cool Gray Vans Auténtico Pewter / True White Vans Auténtico Imperial Azul / Negro Zapatillas de golf adidas W Adipower Boost de adidas para mujer Claro Gris / Correr Blanco / Flash Rojo , Sam Edelman - Sandalia de mujer Liliana Slide Gamuza de Caramelo Dorado , Sandalia de diapositiva de Delilah de mujer de Jack Rogers Oro blanco Sandalia Super Cool Slide de Aerosoles para mujer Coral Sandalia tobogán X-Band con plataforma Mikenzie de Gentle Souls para mujer Coñac , Prop & eacute; t Womens Aurora Slide Rubí , Taryn Rose Women s Lana Sheep Nappa Slide Sandalia Negro Zapatillas de skate DC Women s Villain SE Slip-on Oro rosa , Botines moldeados A-Game para mujer Boombah - 15 opciones de color - Varios tamaños Negro / Naranja Glerups Unisex G-01 - Botas de fieltro Carbón , Zapatilla de mujer Old Friend Scuff Púrpura Mocasines de vestir de punta estrecha para mujer de Me Too Women Negro

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 EN/ Zapatilla 19823 Cloudster para mujer Magenta Cloudster/ Berry f07da42 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

For email to reach me, the word