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```      MATH TOOLS NEWSLETTER - OCTOBER 2, 2009 - No. 80

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***FEATURED ACTIVITY
Activity: Printable compass / straightedge construction
worksheets - Math Open Reference
http://mathforum.org/mathtools/activity/87354/
John Page
A web page that contains a list of 35 printable worksheets
for compass and straightedge constructions. Each printable
sheet has 2 or 3 problems and links back to the pages
interactively explaining the constructions needed. Each
sheet has a space for student name.

***FEATURED ACTIVITY
Activity: A Japanese Temple Problem
http://mathforum.org/mathtools/activity/87146/
Pat Ballew: Explorations in Geometry
In this guided Geometer's Sketchpad exploration, students
use their knowledge of tangent circles to discover a
relationship between the radii of three circles which are
mutually tangent to each other and an external line. This
proof was drawn up on a wooden block and hung in a temple
in Gunma prefecture of Japan in the early 1800's. The
practice of hanging such proofs was called Sangaku.

***FEATURED ACTIVITY
Activity: Math Operations in Lists
http://mathforum.org/mathtools/activity/85103/
Pat Ballew: TI-82 Users Guide
These instructions detail mathematical operations that can
be used on lists or sequences of numbers with the TI-82.
They include questions to test students' understanding,
with answers at the bottom of the page.

***FEATURED TOOL
Tool: Function Grapher Online
http://mathforum.org/mathtools/tool/83600/
Amir Rashedi
Graph functions and find roots (zeros) of functions without
guesswork. Specify domain for functions, drag the graphs
and rotate the axes.

***FEATURED TOOL
Tool: Abacus v1.4
http://mathforum.org/mathtools/tool/80580/
Dana M. Proctor
The Abacus Java Applet/Application is an implementation of
an Abacus counting machine. The machine displays a total
for the number represented by the machine's current state
in addition to each digits value. The program provides a
learning tool to teach basic concepts of the base 10
counting system.

***FEATURED TOOL
Tool: Paramertic Surfaces in Rectangular Coordinates
http://mathforum.org/mathtools/tool/83946/
This 3D grapher graphs a parametric surface defined in
rectangular coordinates. The user enters parametric
formulas for the x, y, and z coordinates and the applet
draws the corresponding surface in 3D. The surface can be
rotated in real time by the user with the mouse and its
opacity can be changed. The second version of the grapher
is much older and slower as it is written in AS1, but it
has a few practice problems that might be of interest.

***FEATURED TOOL
Tool: The Abacus in Various Number Systems
http://mathforum.org/mathtools/tool/81628/
Alexander Bogomolny
An interactive Java applet showing one or two Russian
abacuses with options to select the base of the number
system and the number of wires. The applet displays the
number matching the current configuration and performs
an automatic carry. The abaci can be synchronized so that
adding to one removes an equal number from the other.
Bogomolny links to a page discussing the history and use
of the abacus.

***FEATURED TOOL
Tool: Suan Pan in Various Number Systems
http://mathforum.org/mathtools/tool/81629/
Alexander Bogomolny
An interactive Java gadget simulating suan pan -- the Chinese
abacus. Options include selecting the number system base
and the number of wires. The applet displays the number
matching the configuration and performs an automatic carry.

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