Geogebra/C2/Understanding-Quadrilaterals-Properties/English-timed

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Time Narration


00:00 Hello everybody.
00:02 Welcome to this tutorial on Understanding Quadrilaterals Properties in Geogebra.
00:08 Please note that the intention of this tutorial is not to replace the actual compass box
00:14 Construction in GeoGebra is done with a view to understand the properties.
00:19 We assume that you have the basic working knowledge of Geogebra.
00:24 If not, please visit the spoken tutorial website for the relevant tutorials on Geogebra.
00:30 In this tutorial, we will learn to construct quadrilaterals

Simple quadrilateral and

Quadrilateral with diagonals

And also, learn their properties

00:42 To record this tutorial I am using
00:45 Linux operating system Ubuntu Version 11.10,

Geogebra Version 3.2.47

00:55 We will use the following Geogebra tools for construction
01:00 Circle with centre through point

Polygon

Angle

Parallel line

Segment between two points and

Insert text

01:10 Let's switch on to the new Geogebra window.
01:13 To do this click on Dash home, Media Applications.
01:17 Under Type, Education and Geogebra.
01:25 Let us now construct a circle with center 'A' and which passes through point 'B'.
01:30 To do this, click on the “Circle with Center through Point” tool from the toolbar.
01:35 Click on the drawing pad.

Point 'A' as center.

01;38 And then click again we get point 'B'.

The circle is complete.

01:44 Let us construct an another circle with center 'C' which passes through 'D'.
01:49 Click on the drawing pad. It shows point 'C'.
01:53 Then click again we get point 'D'.

The two circles intersect at two points.

02:00 Click on the “Intersect Two Objects” tool below the “New Point”

Click on the points of intersection as 'E' and 'F'.

02:10 Next, click “Polygon” tool
02:16 Click on the points 'A', 'E', 'C', 'F' and 'A' once again.

Here a quadrilateral is drawn.

02:32 We can see from the “Algebra View” that 2 pairs of adjacent sides are equal.
02:38 Do you know why? Can you figure out the name of this quadrilateral?
02:43 Let us now save the file. Click on “File”>> "Save As"
02:48 I will type the file name as "simple-quadrilateral" click on “Save”.
03:04 Let us now construct a Quadrilateral with diagonals.
03:08 Let's open a new Geogebra window,

click on “File” >> ”New ”

03:16 Select the “Segment between Two Points” tool from the toolbar.

To draw a segment.

03:23 Click on the drawing pad, point 'A' and then on 'B'.

Segment 'AB' is drawn.

03:30 Let's construct a circle with center 'A' and which passes through point 'B'.
03:36 To do this click on the “Circle with Centre through Point” tool.
03:40 Click on the point 'A' as centre and then on point 'B'.

Select the “New Point” tool, from the toolbar.

click on the circumference as point 'c'.

03:57 Let us join 'A' and 'C'.

Select the “Segment between Two Points” tool

04:03 Click on the points 'A' and 'C'.

Let's now construct a parallel line to segment 'AB' which passes through point 'C'.

04:13 To do this select the "Parallel Line" tool from the toolbar.

Click on the point 'C'

and then on segment 'AB'.

04:25 We repeat the process for the point 'B'.

Click on the point 'B'

and then on segment 'AC'.

04:33 Notice that the parallel line to segment 'AB'

and parallel line to segment AC intersect at a point.

Let's mark the point of intersection as 'D'.

04:47 Next using the “Segment between Two Points” tool,

let's connect the points

'A' 'D', 'B' 'C'

05:01 We see that a Quadrilateral ABCD with diagonals AD and BC is drawn.
05:09 The diagonals intersect at a point.

Let us mark the point of intersection as 'E'.

05:20 Using the “Distance” tool,

let's check whether the diagonals bisect each other

05:25 Under the “Angle” tool, click on the “Distance or Length” tool.
05:30 Click on the points A, E, E, D, C, E, E, B
05:47 Next, we will check whether the diagonals are perpendicular bisectors.
05:51 To measure the angle, click on the “Angle” tool.

Click on the points A,E,C C,E,D.

06:08 Let us now select the “Move” tool from the toolbar.

Use the “Move” tool to move the point 'A'.

06:16 Click on the 'Move' tool,

place the mouse pointer on 'A' and drag it with the mouse.

Notice that the diagonals always bisect each other

and are perpendicular bisectors.

06:35 Let us save the file now.

Click on “File”>> "Save As".

I will type the filename as "quadrilateral"

click on “Save”.

06:53 With this we come to the end of this tutorial.

Let us summarize.

07:01 In this tutorial, we have learnt to construct quadrilaterals using the tools -
07:06 'Circle with centre through point', 'Polygon', 'Angle',

'Parallel line', 'Segment between two points' and 'Insert Text'

07:15 We also learnt the properties of
  • Simple quadrilateral and
  • Quadrilateral with diagonals
07:21 As an assignment I would like you to Draw a line segment AB

Mark a point C above the line

Draw a parallel line to AB at C

07:33 Draw two points D and E on the Parallel Line

Join points AD and EB.

07:43 Draw perpendicular lines to segment AB from D and E

Mark the points F and G of the perpendicular lines on AB

Measure distance DE and height DF

08:01 The output of the assignment should look like this.
08:08 Watch the video available at this url.
08:11 It summarises the Spoken Tutorial project

If you do not have good bandwidth, you can download and watch it

08:18 The Spoken Tutorial Project Team

Conducts workshops using spoken tutorials Gives certificates to those who pass an online test

08:27 For more details, please write to

contact@spoken-tutorial.org

08:34 The Spoken Tutorial Project is a part of the Talk to a Teacher project

It is supported by National Mission on Education through ICT, MHRD, Government of India More information on this Mission is available at this link


08:49 This is Madhuri Ganapathi from IIT Bombay signing off.

Thanks for joining


Contributors and Content Editors

Madhurig, Minal, PoojaMoolya, Pratik kamble, Sandhya.np14