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 of:
01:00 * Circle with center 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 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 summarizes 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