Applications-of-GeoGebra/C2/Introduction-to-Trigonometry-Using-GeoGebra/English-timed
From Script | Spoken-Tutorial
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 dialog 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 dialog 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 dialog-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. |
08:45 | The Spoken Tutorial Project team conducts workshops and gives certificates.
For more details, please write to us. |
08:53 | Please post your timed queries on this forum. |
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. |