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 sized 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^2h
10:13 The output of the assignment should look like this.
10:19 Watch the video available at this URL
10:23 It summarises 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