Applications-of-GeoGebra/C2/Introduction-to-Trigonometry-Using-GeoGebra/English-timed

Time	Narration
00:01	Welcome to this tutorial on Introduction to Trigonometry using GeoGebra.
00:08	In this tutorial, we will learn how to construct, A unit circle
00:14	A right triangle inside the unit circle using GeoGebra.
00:19	To follow this tutorial, you should be familiar with the GeoGebra interface
00:26	basics of geometry, trigonometry and graphs.
00:31	Here I am using- Ubuntu Linux OS version 14.04 GeoGebra 5.0.388.0 hyphen d.
00:43	I have already opened the GeoGebra interface.
00:47	Click on Move Graphics View tool.
00:51	Drag the origin to the centre of the Graphics view.
00:56	Under Move Graphics View, click on Zoom In tool.
01:00	Then click on screen in Graphics view.
01:03	This will magnify the Graphics view.
01:08	Click on Slider tool and then click on the screen in Graphics view.
01:16	Slider dialogue appears in the Graphics view.
01:20	By default, the Number radio-button is selected.
01:24	In the Name field, type radius.
01:28	Set Minimum value as 1, Maximum value 5 and Increment of 0.1.
01:39	Click OK button.
01:41	This creates a number slider named radius.
01:45	Using the slider, radius can be changed from 1 to 5 in increments of 0.1.
01:52	Click on Slider tool and then click on the screen in Graphics view.
01:59	Slider dialogue box appears.
02:01	This time, select Angle radio button.
02:05	Minimum, Max and Increment should be 0 degrees 360 degrees and 1 degree, respectively.
02:12	Click OK.
02:15	This sets up alpha slider, on which angle alpha can be changed from 0 to 360 degrees.
02:23	Click on Circle with Center and Radius tool.
02:28	Place the cursor on the origin (0,0) and click on it.
02:34	Circle with Centre and Radius text box appears.
02:39	In text box, type radius and click OK .
02:45	A circle with center A at the origin is drawn. Please note, we are using A for O(0,0).
02:54	Drag the radius slider from 1 to 5 to change the radius of the circle.
03:00	Drag it to 1 to have a unit circle.
03:04	Click on Segment tool.
03:07	Click on the circumference of the circle at the x Axis. This creates point B.
03:16	Then click on point A to draw segment AB.
03:21	Now click on Angle with Given Size tool.
03:25	Click on point B, then point A.
03:31	Angle with Given Size text-box appears.
03:35	In the text box, delete 45 degrees and select alpha α from the symbol menu.
03:43	Leave direction at counter clockwise, click OK.
03:48	Angle B prime AB is created which is equal to beta β which is equal to alpha α.
03:57	Drag the alpha α' slider from 0 to 360 degrees.
04:03	B prime moves in counter clockwise direction around the circle as alpha increases.
04:10	Now drag the alpha α slider so that beta β value is between 50 and 60 degrees.
04:18	Click on Point tool and click outside the circle to create point C.
04:26	In the Algebra view, double-click on point C to change its coordinates.
04:32	Type x B prime as x-coordinate and y-coordinate as zero and press Enter.
04:43	This will shift point C right under B prime.
04:48	Click on Segment tool.
04:51	Click on points B prime and A to join them.
04:57	This forms the hypotenuse of the right triangle A C Bprime.
05:03	Now using Segment tool join B prime and C.
05:08	A right angle is formed at C angle A C Bprime.
05:14	Angle B prime A C is equal to alpha which is equal to beta degrees.
05:21	Drag the alpha slider from 0 degree to 360 degrees to see how alpha changes.
05:30	Let us enhance the visibility of the triangle.
05:34	Double-click on angle beta β. Click on Object properties.
05:40	Click on the Color tab. Leave color as green.
05:45	Increase Opacity to 25.
05:49	Click on Style tab. Increase size to 50.
05:55	Change the Decoration to arrow pointing counter clockwise.
06:00	Close the Preferences dialogue-box.
06:03	I will now change the properties of the triangle segments.
06:07	To change the colour of the segments, double-click on segment A B prime. Select Object Properties.
06:16	Click on Color tab. Select blue.
06:20	Similarly, change the colors of C B prime to red and of AB to orange.
06:32	To rename the segments, right-click on segment A B prime.
06:39	Choose Rename option.
06:43	Type c in the name field and click OK.
06:48	Similarly, rename C B prime to a and AC to b.
06:59	If you wish, you may change the Line Thickness and the Line Style in the Style tab.
07:09	In Algebra view, click and highlight segment a.
07:13	Holding the Shift key down, highlight all 3 segments.
07:20	In Graphics view, click on Hidden option.
07:25	All three labels are hidden.
07:28	Now let us change x Axis units to radians.
07:32	Double click on x axis in Graphics view then on Object Properties.
07:39	In the Object Properties menu, click on Preferences Graphics then on x Axis.
07:47	Check the Distance option, select pi over 2.
07:53	Select the Ticks first option.
07:56	Close the Preferences box.
07:59	Units of x-axis are in radians with the intervals shown.
08:05	GeoGebra will convert degrees of angle alpha to radians.
08:11	Let us summarize.
08:13	In this tutorial, we have learnt how to use GeoGebra to construct a unit circle and a right triangle inside it.
08:22	As an Assignment, Try constructing circles with radius 2 and 3 units.
08:29	Draw right triangles in these circles.
08:32	Also try different styles, opacity & thickness.
08:37	The video at the following link summarizes the Spoken Tutorial project. Please download and watch it.
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08:57	Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India.
09:05	More information on this mission is available at this link.
09:10	This is Vidhya Iyer from IIT Bombay signing off. Thank you for joining.

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