Geogebra/C2/Symmetrical-Transformation-in-Geogebra/English-timed

Time	Narration
00:00	Hello everybody. Welcome to this tutorial on Symmetrical Transformation in Geogebra.
00:06	In this tutorial we will learn Symmetrical transformations such as:
00:11	* Line symmetry
00:12	* Rotation symmetry
00:13	* and also learn to enlarge figure with scale and position.
00:17	We assume that you have the basic working knowledge of Geogebra.
00:21	If not, for relevant tutorials, please visit our website.
00:26	To record this tutorial, I am using Ubuntu Linux OS Version 11.10,
00:31	Geogebra Version 3.2.47.0.
00:35	We will use the following Geogebra tools:
00:37	* Reflect Object about Line
00:39	* Rotate Object around Point by Angle
00:42	* Dilate object from a Point by Factor
00:45	* Semicircle through Two points
00:47	* Regular Polygon and
00:49	* Perpendicular bisector
00:51	Definition of Transformation-
00:53	Symmetrical transformation of a geometric figure is:
00:57	A change in its position, size or shape on a coordinate plane.
01:02	Original figure is called Object.
01:04	Transformed figure is called Image.
01:07	Reflection symmetry:
01:09	* Is also called as Line symmetry.
01:11	* A type of symmetry where one half is the reflection of the other half.
01:15	* You could fold the image and have both halves match exactly.
01:20	* Line of Symmetry is the line over which the figure is reflected.
01:24	Let's switch to Geogebra window.
01:27	Look on Dash home >> Media Apps >> under Type >> choose Education >> and Geogebra.
01:37	For this tutorial, I am closing the Algebric view.
01:40	Click on Close button on Algebric view.
01:47	Let's start with Line of symmetry.
01:50	First, let's construct an equilateral triangle.
01:53	Select Regular Polygon tool from the toolbar.
01:57	Click on drawing pad points A ,B, and enter 3 for the number of sides.
02:08	An equilateral triangle ABC is drawn.
02:11	Let's draw a perpendicular bisector to one of the sides of triangle.
02:15	Select Perpendicular Bisector Tool and click on side AC.
02:26	Select the Point tool and create a point inside the triangle.
02:31	Move the point D towards one of the vertices .
02:38	Right click on point D and select Trace On.
02:43	Select Reflect Object about Line tool from the tool bar.
02:48	Click on the point D.
02:49	This will highlight point D.
02:52	Click on Perpendicular Bisector.
02:55	This will produce reflected image D' on the other side of perpendicular bisector.
03:01	D' is mirror image of point D.
03:04	Set Trace On for the point D.
03:08	Let us move the point D along the triangle, using Move tool.
03:11	Click on the first option under Move tool from the toolbar.
03:22	Click on figure with the mouse.
03:25	Drag it tracing the triangle .
03:28	Now release the mouse button.
03:31	What do you notice ?
03:32	Here perpendicular bisector is the line of symmetry.
03:36	D is the object and D' is the image.
03:39	Let's reflect a semicircle about a line.
03:43	Let's draw a semicircle.
03:44	Click on the Semicircle through Two points tool. Mark point E and then F.
03:56	Click on segment between two points.
04:02	Mark points G and H. A line is drawn.
04:06	Let's change the property of the line.
04:08	Right click on the line, Object Properties. Click on Style, change Style.
04:21	Select Reflect Object about Line tool from the toolbar.
04:27	Click on the semicircle EF.
04:31	Click on line GH.
04:34	This will produce the reflected image E'F' on the other side of line GH. What does the figure look like now ? It looks like a circle.
04:45	Let us save this file now.
04:47	Click on File >> Save As.
04:50	I will type the file name as Line-symmetry and click on Save.
05:05	Next, let us learn to Rotate the Object around a Point by Angle.
05:12	Definition of Rotation-
05:15	A rotation is a transformation that turns a figure around a fixed center by an angle.
05:21	If the figure appears unchanged then the figure has rotation symmetry.
05:29	You can rotate object at any degree measure. Rotation can be clockwise and counterclockwise.
05:39	Let's open a new Geogebra window.
05:41	click on File >> New.
05:47	Let us construct a square.
05:49	click on Regular Polygon tool from the toolbar.
05:55	Click on the drawing pad.
05:57	Mark points A and B.
05:59	A dialog box opens.
06:01	Click on OK.
06:03	A square ABCD is drawn.
06:05	Click on Rotate Object around a Point by Angle tool.
06:13	Click on the Square ABCD.
06:16	This will highlight the square.
06:18	Next Click on any one of the vertices.
06:20	I will click on A.
06:23	A dialog box opens.
06:25	Type 60 in the Angle field
06:30	Select °(Degree) from first drop down list.
06:35	Select the option clockwise. Click on OK.
06:40	This will rotate the square clockwise at the point of selection, with the angle of 60°.
06:44	The rotated image A`B`C`D` is formed.
06:49	Let's move this figure aside using Move tool.
07:00	Next, let's dilate or enlarge object from point by factor.
07:09	Dilation:
07:11	Dilation or enlargement is a transformation
07:14	in which a figure is enlarged using a scale factor.
07:23	Let's draw a triangle using the Polygontool,
07:28	E , F , G. Click on E again to complete the triangle.
07:36	Click on New Point tool and
07:40	mark a point H.
07:44	Click on Dilate Object from Point by Factor tool.
07:51	Click on the triangle EFG.
07:54	This will highlight the triangle.
07:55	Click on the point 'H'.
07:57	A dialog box opens.
08:00	Type value of 2 in the number field.
08:04	Click on OK.
08:09	This will dilate or enlarge the object twice.
08:16	Click on segment between two Points, join points H,E,E'.
08:33	join points H,G,G'.
09:01	join points H,F,F'.
09:15	Here, you can see that H is the point of dilation.
09:21	You can enlarge object as many number of times as you wish, by typing the value of Factor.
09:28	Let us save this file now.
09:30	Click on File >> Save As.
09:33	I will type the file name as Dilate-triangle.
09:48	Click on Save. With this we come to the end of this tutorial.
09:55	Let's summarize.
09:58	In this tutorial we learnt:
10:00	* Reflection about a line.
10:02	* Rotation of an object at a point.
10:05	* Enlargement of an object by a scale factor.
10:09	As an assignment I would like you to:
10:11	Draw a pentagon.
10:12	Use Regular Polygon tool to draw. (Hint:sides=5).
10:17	Draw a perpendicular bisector to one of the sides of the pentagon.
10:21	Create a point inside the pentagon.
10:25	Set Trace On for the point.
10:27	Get reflection of the point about the perpendicular bisector.
10:31	Set Trace On for the image point.
10:34	Trace the pentagon to see if you have selected the correct line of symmetry.
10:44	Rotate the original pentagon counter clockwise in 135° at a point.
10:49	Dilate the pentagon at a point by the factor of 3.
10:56	The assignment should look like this.
11:03	Watch the video available at this URL.
11:06	It summarizes the Spoken Tutorial project.
11:09	If you do not have good bandwidth,you can download and watch it.
11:12	The Spoken Tutorial Project Team : Conducts workshops using the spoken tutorials.
11:17	Gives certificates to those who pass an online test.
11:20	For more details, please write to contact@spoken-tutorial.org.
11:26	Spoken Tutorial Project is a part of the Talk to a Teacher project.
11:29	It is supported by the National Mission on Education through ICT, MHRD, Government of India.
11:35	More information on this Mission is available at this link.
11:39	This is Neeta Sawant from SNDT University Mumbai, signing off. Thanks for joining.

Contributors and Content Editors

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