Pi Day Pics

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Mar 102015
 
Here’s a great set of pictures for math teachers and other pi fans, found at NETWORKWORLDPi plate wikipedia
This year Pi Day is special, because it happens on 3/14/15, and the decimal representation of pi is 3.1415 . . .
Some folks are calling it Pi Day of the Century – we’ll see.
Dec 292014
 

This is a great exercise for Common Core Geometry instruction in the area of transformations.

HINT: highlight a slider’s button, then use your cursor keys for fine adjustment; play around with the numbers to get pleasing shapes.

Use slider n for number of iterations
Use slider r for rotation in 0.001 increments
Use slider d for dilation in 0.001 increments
Build command structure in 3 steps:
Enter Dilate[poly1, d^i], where i = 1, 2, 3 to find pattern
Enter Rotate[Dilate[poly1, d^i], i r π], where i = 1, 2, 3 to find pattern
Enter Sequence[Rotate[Dilate[poly1, d^i], i r π], i, 1, n, 1]
This Sequence command should work for all polygons.

The downloadable file can be found here.

My other GeoGebraTube apps can be found here.

Dec 292014
 

Number of diagonals in a polygon:
If n = number of vertex points, then D = number of diagonals = n(n-3)/2.
Slider n controls the number as well as the color. In the Advanced tab,
Red = n / 36, Green = 1 – n / 36, and Blue = 0, so the color changes from Green
to Red as the number of sides moves from 3 to 36.
reference: I modified sonom’s idea from http://tube.geogebra.org/material/show/id/137056

The downloadable file can be found here.

My other GeoGebraTube apps can be found here.

Dec 292014
 

An epitrochoid is the path traced by a point on a circle (M)
that travels on the outside of another circle (E).
This can be used to model the path of the Moon (M) in orbit around the Earth (E).
There are about 13.3 revolutions(n) of the Moon about the Earth in one year.
-credit-Malin Christersson-http://www.geogebratube.org/material/show/id/87141

The downloadable file can be found here.

My other GeoGebraTube apps can be found here.

Polar Vector Clock

 GeoGebra  Comments Off
Dec 292014
 

Polar definitions: Sec=90°-(6a)°, Min=90°-(a/10)°, Hour=90°-(a/120)°
NOTE 1: when using polar coordinates a semicolon is needed
NOTE 2: “Alt-o” (letter O, not number 0) gives degree symbol
Vectors are used for clock hands.
-from wikimedia commons: the clock face background,
and set at Layer=0; other graphics are at Layer=1
-Animation speed = 0.00023148 to move second hand accurately
-credit: Malin Christersson-http://www.malinc.se/math/geogebra/slideren.php

The downloadable file can be found here.

My other GeoGebraTube apps can be found here.