Geogebra/C3/Mensuration/English-timed

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Time Narration
00:00 Hello everybody Welcome to this tutorial on Mensuration in Geogebra.
00:06 In this tutorial, we will learn to find:
00:09 * Area and perimeter of rhombus
00:12 * Surface area of sphere and cone
00:15 * Volume of sphere and cone
00:20 We assume that you have the basic working knowledge of Geogebra.
00:24 For Relevant tutorials on Geogebra,
00:27 please visit our website.
00:31 To record this tutorial, I am using:
00:33 Ubuntu Linux OS Version 11.10
00:38 Geogebra Version 3.2.47.0
00:42 We will use the following Geogebra tools:
00:46 * Segment between two points
00:48 * Circle with center and radius
00:51 * Ellipse
00:52 * Polygon
00:54 * New point and
00:56 * Insert text
00:57 Let's open a new Geogebra window.
01:00 Click on Dash home and Media Apps. Under Type, choose Education and Geogebra
01:13 Let's find the area of a rhombus.
01:15 Let's use the file quadrilateral.ggb of the previous tutorial.
01:20 Click on File, Open, click on quadrilateral.ggb.
01:27 Click on Open.
01:29 Area of the Rhombus =1/2 * product of diagonals.
01:34 To demonstrate it:
01:36 Click on the Insert text tool.
01:39 Click on the drawing pad.

A text box opens.

01:44 Area of the rhombus =+(1/2 g f)

Open the double quotes(“), type:

Area of the rhombus = close the double quotes

+ for concatenation open the brackets, type:

1/2 space f space g

close the bracket

f and g are the diagonals of the rhombus.

02:09 Click OK.
02:11 Area of rhombus is displayed here on the drawing pad.
02:14 Next, let's find perimeter.
02:17 Click on the Insert text tool.
02:19 Click on the drawing pad. A text box opens.
02:22 Open the double quotes(“) type:

Perimeter of the rhombus =+(4 a)

close double quotes '+' open the brackets

4 space 'a' close the brackets

a is the side of the rhombus.

02:44 Click OK.
02:46 Perimeter of rhombus is displayed here on the drawing pad.
02:50 Let's now save the file.
02:53 Click on File and Save As.
02:55 I will type the filename as rhombus-area-perimeter
03:12 Click on Save.
03:17 As an assignment, I would like you

to find area and perimeter of trapezium,

03:22 use output of file cons-trapezium.ggb.
03:27 Rename object g as b.
03:30 Formula for area = (half sum of parallel sides) * (vertical height) = (a+b)/2* h
03:40 Formula for perimeter =(sum of the sides) =(a+b+c+d)
03:49 The output of the assignment should look like this.
03:54 Let's open a new Geogebra window to draw a sphere.
03:58 Click on File , New
04:01 Click on the Circle with center and radius tool from the toolbar.
04:06 Click on the drawing pad point A.

A text box opens.

04:11 Enter value 2 for radius.
04:13 Click OK.
04:15 A circle with center A and radius 2cm is drawn.
04:19 Select New point tool from tool bar, mark a point B on the circumference of the circle.
04:26 Select Segment between two points tool.
04:29 Join points A and B as radius of the circle.
04:34 Let's draw an ellipse CDE in the horizontal direction,

to touch the circumference of the circle.

04:42 Click on Ellipse tool.
04:45 Mark points C and D diagonally opposite to each other on the circumference

and a third point E inside the circle.

04:56 Here a sphere is drawn.
04:59 Let's now find the Surface area of the sphere.
05:03 Click on Insert text tool.
05:05 Click on the drawing pad. A text box opens.
05:08 Please find the special characters in the drop down list in the text box.

Scroll down to find π (pi).

05:17 open double quote, type:

Surface area of the sphere = +( 4 π a2)

close double quote plus open the bracket 4 space

select π from the list space

a select 'square' from the list

close the bracket.

05:45 Click OK
05:47 surface area of the sphere is displayed here.
05:52 Let me click on it and drag it, place it below.
05:56 Next, let's find Volume.
05:59 Click on the Insert Text tool.
06:00 click on the drawing pad, Text box opens.
06:03 open double quote type:

Volume of the sphere = +(4/3 π a^3)

close double quote plus open the bracket 4/3 space

select π from the list space a

select cube from the list close the bracket

06:31 click OK.
06:34 Volume of the sphere is displayed here.
06:36 Let me click on it and drag it to place it below.
06:40 Next, let's draw a cone.
06:43 Click on Polygon tool.
06:45 Click on points C , D and an external point F

and C once again.

06:53 Select Segments between two points tool

join points F and A.

06:59 We get height of the cone.
07:03 Let me rename the object b as h which denotes height of the cone.
07:08 Right click on object b.
07:09 Click on Rename.
07:11 Replace b with h click OK.
07:15 Let me also

Rename the object c_1 as s which denotes slant height of cone.

07:21 Right click on object c_1.
07:23 Click on Rename.
07:24 Replace c_1 with s.
07:26 Click OK.
07:28 Let's find now surface area and volume of the cone.
07:33 We can use either the Insert text tool from the tool bar or we can use the Input bar.

I will use the Input bar.

07:40 Please find the special characters in the drop down list of the Input bar.
07:44 Scroll down to find π.
07:48 Type in the input bar:

Area = (π a s + π a²)

Surfacearea = open the bracket

Select 'π' from the list space a space s

plus select π from the list space a

Select square from list close the bracket

press Enter.

08:15 Surface Area of the cone is displayed in the Algebra view.
08:20 Please note when we use the Input bar

answer appears in the Algebra view.

08:26 Let's find Volume.
08:29 Volume =(1/3 π a² h)

Volume =open bracket

1/3 space select 'π' from the list space a

Select square from list space h close the bracket

Press Enter.

08:50 Volume of the cone is displayed here in the Algebra view.
08:55 Lets now save the file. Click on file Save As.

I will type the file name as Sphere-cone.

09:08 Click on Save.
09:10 With this we come to the end of this tutorial.
09:14 Let us summarize.
09:18 In this tutorial we have learnt to find:
09:20 * Area and perimeter of rhombus
09:24 * Surface Area of sphere and cone
09:27 * Volume of sphere and cone.
09:30 We have also learnt to draw sphere and cone.
09:36 As an assignment, I would like you to find Surface area and volume of cylinder.
09:43 Draw 2 ellipses of same size, one below the other.
09:47 Connect edges of ellipses.
09:50 Use Center tool, find center of one ellipse.
09:54 Join center and edge.
09:56 Rename object b as h and e as r.
10:01 Surface area = 2 π r(r + h)
10:07 Volume = π r^2 h
10:13 The output of the assignment should look like this.
10:19 Watch the video available at this URL.
10:23 It summarizes the Spoken Tutorial project.
10:26 If you do not have good bandwidth, you can download and watch it.
10:31 The Spoken Tutorial Project Team :
10:33 Conducts workshops using spoken tutorials.
10:36 Gives certificates to those who pass an online test.
10:40 For more details, please write to

contact@spoken-tutorial.org

10:48 Spoken Tutorial Project is a part of the Talk to a Teacher project.
10:52 It is supported by the National Mission on Education through ICT, MHRD, Government of India.
10:59 More information on this Mission is available at this link.
11:06 This is Madhuri Ganapathi from IIT Bombay, signing off.

Thanks for joining

Contributors and Content Editors

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