Difference between revisions of "GeoGebra-5.04/C2/Basics-of-Triangles/English-timed"
From Script | Spoken-Tutorial
PoojaMoolya (Talk | contribs) (Created page with "{|border=1 ||'''Time''' ||'''Narration''' |- || 00:01 || Welcome to this Spoken tutorial on '''Basics of Triangles''' in '''GeoGebra'''. |- ||00:06 || In this tutorial...") |
PoojaMoolya (Talk | contribs) |
||
| Line 39: | Line 39: | ||
|- | |- | ||
||00:45 | ||00:45 | ||
| − | || '''GeoGebra''' version 5. | + | || '''GeoGebra''' version 5.0.438.0-d |
|- | |- | ||
Latest revision as of 17:32, 4 October 2019
| Time | Narration |
| 00:01 | Welcome to this Spoken tutorial on Basics of Triangles in GeoGebra. |
| 00:06 | In this tutorial we will, learn to Draw a triangle and measure its angles |
| 00:13 | Display perimeter and area of the triangle |
| 00:17 | Show that sum of the angles of a triangle is 180 degrees |
| 00:22 | Show that exterior angle is equal to sum of the interior opposite angles |
| 00:28 | Also we will learn to draw, |
| 00:31 | Altitudes of the triangle and locate the orthocenter
An incircle to a triangle. |
| 00:38 | To record this tutorial, I am using; Ubuntu Linux OS version 14.04 |
| 00:45 | GeoGebra version 5.0.438.0-d |
| 00:51 | To follow this tutorial, learner should be familiar with Geogebra interface. |
| 00:58 | If not for relevant GeoGebra tutorials please visit our webiste. |
| 01:04 | I have opened a new GeoGebra window. |
| 01:07 | Before I begin, I will increase the font size to show the icons clearly. |
| 01:13 | Go to Options menu and select Font Size. |
| 01:17 | From the sub-menu select 18 pt radio button. |
| 01:22 | For this tutorial I will uncheck the Axes.
Right-click on the Graphics view. |
| 01:29 | And from the Graphics menu, uncheck the Axes. |
| 01:33 | Now we will draw a triangle ABC. |
| 01:36 | Click on Polygon tool. |
| 01:39 | Click on the Graphics view to draw three vertices A, B and C. |
| 01:49 | Then click on vertex A again to complete the triangle. |
| 01:53 | As we draw the triangle, observe the corresponding values in the Algebra view. |
| 01:59 | It displays: Coordinates of vertices
Lengths of the sides and Area of the triangle. |
| 02:09 | Now let us learn to measure the angles of the triangle. |
| 02:13 | Click on the Angle tool.
Click on the vertices B A C, |
| 02:23 | C B A |
| 02:29 | A C B |
| 02:35 | Values of the angles alpha, beta and gamma are displayed in the Algebra view. |
| 02:42 | Now we will move the overlapping labels. |
| 02:46 | Click on the Move tool and drag the labels to see them clearly. |
| 02:54 | Let us display the perimeter and area of the triangle. |
| 02:58 | Click on the Angle tool drop-down and select Distance or Length tool. |
| 03:05 | Click on the triangle ABC. |
| 03:08 | Perimeter of triangle is displayed on the triangle. |
| 03:12 | Now select the Area tool and click on the triangle ABC to display it. |
| 03:19 | Next we will find the sum of the angles of the triangle ABC using input bar. |
| 03:25 | In the input bar, open parentheses. |
| 03:29 | Inside the parentheses, select alpha from the symbols table.
Now type plus sign, select beta. |
| 03:39 | Once again type plus sign and select gamma.
Press Enter. |
| 03:47 | Observe the value of angle delta in the Algebra view.
It is equal to 180 degree. |
| 03:54 | Now click on the Slider drop-down and select Text tool.
Then click on the Graphics view. |
| 04:03 | A text window opens on the Graphics view. |
| 04:07 | The Text tool has, An Edit box to type text |
| 04:12 | A Preview box to show the preview of the typed text
A Latex formula check box |
| 04:19 | Symbols drop-downs and
Objects drop-down. |
| 04:25 | Now we will show that, the sum of the angles of the triangle is 180 degrees. |
| 04:30 | In the Edit text box type,
Sum of the Angles is equal to |
| 04:35 | Select alpha from Objects drop-down + select beta from Objects drop-down + select gamma from Objects drop-down equal to select delta from Objects drop-down. |
| 04:50 | Observe the entered text and the values of the selected angles in the Preview box. |
| 04:56 | Click on the OK button at the bottom. |
| 04:59 | The text will be displayed on the Graphics view. |
| 05:03 | Using the Move tool drag the points A, B or C. |
| 05:08 | Observe that, the sum of the angles of the triangle always shows 180 degrees. |
| 05:14 | Now we will draw a line extending segment BC. |
| 05:18 | Click on the Line tool, then click on points B and C. |
| 05:24 | Using Point tool we will mark a point D on line f next to C. |
| 05:30 | Now we will measure the exterior angle of the triangle ABC. |
| 05:35 | Click on the Angle tool and then click on the points DCA. |
| 05:45 | Using the Move tool, drag the overlapping labels of the angles and points. |
| 05:54 | Now, We will learn to change the colour of angle epsilon. |
| 05:58 | Right-click on angle epsilon.
From the sub-menu, select Object Properties. |
| 06:05 | Preferences window opens. |
| 06:08 | In the Color tab change the colour to Maroon and drag the Opacity slider. |
| 06:15 | Close the Preferences window. |
| 06:18 | Now we will check if exterior angle is equal to sum of interior opposite angles. |
| 06:24 | In the input bar, open the parentheses.
Inside the parentheses, select alpha from the symbols table. |
| 06:33 | Then press plus sign on the keyboard and select beta.
Press Enter. |
| 06:41 | Observe in the Algebra view a new angle tau equal to epsilon is created. |
| 06:48 | Angle tau is the sum of the angles alpha and beta. |
| 06:53 | Using the Move tool drag point C and observe the changes.
We see that angle epsilon is equal to angle tau. |
| 07:03 | Next I will open a new window with triangle ABC and angles already drawn. |
| 07:09 | We will draw altitudes and an orthocentre to the triangle ABC. |
| 07:14 | For this first we will draw external lines on all the sides of triangle ABC. |
| 07:21 | Click the Line tool, then click on points A, B. |
| 07:28 | Similarly click on points B, C and A, C. |
| 07:35 | Now we will draw altitudes to the triangle ABC. |
| 07:39 | Click on the Perpendicular Line tool.
Click on point A and line g. |
| 07:46 | Similarly click on point B and line h.
Click on point C and line f. |
| 07:55 | The three altitudes of the triangle meet at a point. |
| 07:59 | Click on the Intersect tool and mark the point of intersection as D. |
| 08:06 | Point D is the orthocenter of the triangle ABC. |
| 08:10 | Let us rename point D as orthocenter.
Right-click on point D. |
| 08:17 | From the sub-menu select Rename. |
| 08:20 | Rename text box opens. |
| 08:23 | In the Rename text box type Orthocenter.
Click on the OK button at the bottom. |
| 08:30 | Now press Ctrl+ Z to undo the changes. |
| 08:36 | Retain the triangle ABC with angles. |
| 08:40 | Now let's construct angle bisectors to the angles. |
| 08:44 | For this, select the Angle Bisector tool from the tool bar. |
| 08:49 | Click on the points B, A, C. |
| 08:56 | C, B, A |
| 09:02 | A, C, B. |
| 09:08 | Observe that the angle bisectors intersect at a point. |
| 09:12 | Let's mark the point as D using Intersect tool. |
| 09:20 | Let us construct a line perpendicular to segment BC, passing through D. |
| 09:26 | Select the Perpendicular Line tool, click on point D and then on segment BC. |
| 09:34 | Observe that the perpendicular line intersects BC at a point. |
| 09:39 | Let's mark this point as E using Intersect tool. |
| 09:45 | Now, Let's construct a circle with centre D and which passes through E. |
| 09:51 | Click on Circle with Centre through point tool, click on point D and then click on point E. |
| 10:00 | A circle which touches all sides of the triangle is drawn.
This circle is the incircle to the triangle ABC. |
| 10:10 | Let us summarize what we have learnt. |
| 10:13 | In this tutorial we have learnt to, Draw a triangle and measure its angles. |
| 10:20 | Display perimeter and area of the triangle |
| 10:24 | Show that sum of the angles of a triangle is 180 degrees |
| 10:29 | Show that, exterior angle is equal to sum of the interior opposite angles. |
| 10:35 | We have also learnt to draw, Altitudes of the triangle and located the orthocenter. |
| 10:41 | An incircle to a triangle. |
| 10:44 | As an assignment, Draw a circumscribed circle to the triangle. |
| 10:50 | Hint: Draw perpendicular bisectors to the sides of the triangle. |
| 10:55 | Your assignment should look like this. |
| 10:59 | Another assignment- Draw medians to the triangle. |
| 11:04 | Mark the intersection point of medians.
Rename the point as centroid. |
| 11:10 | Hint: Mark midpoints of the sides.
Join the midpoint of each side with the opposite vertex. |
| 11:18 | Your assignment should look like this. |
| 11:22 | The video at the following link summarizes the Spoken Tutorial project.
Please download and watch it. |
| 11:30 | The Spoken Tutorial Project team conducts workshops and gives certificates.
For more details, please write to us. |
| 11:38 | Please post your timed queries in this forum. |
| 11:42 | The Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India.
More information on this mission is available at this link. |
| 11:53 | This is Madhuri Ganapathi from, IIT Bombay signing off.
Thank you for watching. |
