Geogebra/C3/Relationship-between-Geometric-Figures/English
Title of script: Relationship between Geometric Figures
Author: Madhuri Ganapathi
Keywords: Cyclic quadrilateral, Incircle, Compass, Segment between two points, Circle with center through point, Polygon, Perpendicular bisector, Angle bisector, Angle "Regular Polygon , Move, video tutorial.
Visual Cue | Narration |
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Slide Number 1 |
Hello everybody. Welcome to the Geogebra tutorial on Relationship between different Geometric Figures in Geogebra We assume that you have the basic working knowledge of Geogebra. If not, please go through the “Introduction to Geogebra” tutorial before proceeding further. |
Slide Number 2 | Please note that the intention to teach this tutorial is not to replace the actual compass box.
Construction in GeoGebra is done with the view to understand the properties. |
Slide Number 3
Learning objectives |
In this tutorial we will learn to construct
In-circle |
Slide Number 4
System Requirement |
To record this tutorial I am using
Linux operating system Ubuntu Version 10.04 LTS Geogebra Version 3.2.40.0 |
Slide Number 5
GeoGebra Tools used in this tutorial |
We will use the following tools of Geogebra for the construction
|
Switch to Geogebra window
Applications>>Education>>Geogebra |
Let us open the Geogebra window.
Let us now construct a cyclic quadrilateral. |
Click regular polygon tool >> default value 4 >>
click OK >> construct square |
Using the “regular polygon” tool click on any two points on the drawing pad. A dialog box will open with a default value '4'. click on OK.
|
Click move tool>> tilt to angle angle | Using “move” tool
tilt the square to 45^0(degree) angle. To do this place, the mouse pointer on 'A' or 'B' |
Click perpendicular bisector tool>>click point 'A' and 'B' | To construct a perpendicular bisector on segment 'AB'
Select “perpendicular bisector” tool, click on point 'A' and then on 'B' |
Click perpendicular bisector tool>>click segment 'BC' | To construct the perpendicular bisector on 'BC',
we will follow the same process. Select “perpendicular bisector” tool, click on point 'B' and then on 'C' |
Point to the intersection point>> mark point as 'E' | The two perpendicular bisectors intersect at a point .
Let us mark it as 'E' |
Click compass tool>> construct circle | Using the “compass” tool,
draw a circle with centre as 'E' which passes through C . The circle will pass through all the vertices of the quadrilateral Did you know , the cyclic quadrilateral has maximal area among all quadrilaterals having the same sequence of side lengths |
Click on file>>Click on "Save As" >>
type "cyclic_quadrilateral" in file name >> click on OK. |
Lets save this file now.
Click on file then on "Save As". I will type the file name as "cyclic_quadrilateral" and click on save |
Click File>> New window | Let us now construct an incircle.
I will open a new geogebra window |
Click polygon tool>> draw triangle | Using the “polygon” tool
click three points on the drawing pad and draw a triangle 'ABC' |
Click angle tool >> measure the angles |
Select the “angle” tool and measure the angles 'BAC' , 'CBA' and 'ACB'.
click the points in the same direction. |
Draw angle bisectors >> to angles 'BAC' and 'CBA | Lets draw angle bisectors to angles 'BAC' and 'CBA' using “angle bisector” tool |
Hover the mouse on Point of intersection | The two angle bisectors intersect at point .
Mark this point as 'D' . |
click "perpendicular line” tool>>draw perpendicular line | Using “perpendicular line” tool
draw a perpendicular line through 'AB' which passes through 'D' |
Lines meet at 'E' | The perpendicular line intersects 'AB' .
Mark it as 'E' |
Compass tool>>draw circle |
Using the “compass” tool let us draw a circle with radius 'DE' . An in-circle is drawn. With this we come to an end of this tutorial |
Slide number 6
summary |
In this tutorial we have learnt to draw
cyclic quadrilateral and In-circle |
Slide Number 7
Assignment |
Draw triangle ABC
M a point D on BC and join AD Draw in-circles for each triangles ABC, ABD and CBD of radii r, r1 and r2 resp. BE is the height h verify the relationship between r1,r2 and r as (1 -2r1/h)*(1 - 2r2/h) = (1 -2r/h) by moving the vertices of the Triangle ABC |
Show the output of the Assignment | The output should look like this. |
Slide number 8
Acknowledgement |
Watch the video available at
http://spoken-tutorial.org /What is a Spoken Tutorial It summarises the Spoken Tutorial project If you do not have good bandwidth, you can download and watch it |
The Spoken Tutorial Project Team :
Conducts workshops using spoken tutorials Gives certificates to those who pass an online test For more details, contact sptutemail@gmail.com | |
Spoken Tutorial Project is a part
of the Talk to a Teacher project It is supported by the National Mission on Education through ICT, MHRD, Government of India More information on this Mission is available at http://spoken-tutorial.org /NMEICT-Intro | |
Slide Number 9
About the Contributor |
This is Madhuri Ganapathi from IIT Bombay signing off |