Welcome to the Spoken Tutorial on Create Action Object Tools in GeoGebra.
In this tutorial we will learn about free and dependent Objects.
We will also learn to, Create a check-box Create an insert button Insert an input box
To record this tutorial, I am using; Ubuntu Linux OS version 16.04 GeoGebra version 5.0.438.0-d
To follow this tutorial, learner should be familiar with GeoGebra interface. For the prerequisite GeoGebra tutorials, please visit this site.
In this tutorial we will use tangents to a circle tool created in the previous tutorial.
To practise this tutorial you need to download the zip file given in the Code files link.
Extract the downloaded zip file.Locate tangents-circle.ggt file in the extracted folder.
I have already downloaded and extracted the file to my Desktop.
I will right-click on it and Open With GeoGebra.
Click on Tangents to a circle tool and click two points in the Graphics view.
Tangents to a circle are drawn in the Graphics view.
Now I will explain about Free and Dependent Objects.
Let us complete the figure.
Click on the Intersect tool. Mark points of intersection of the tangents to the circle.
Using the Segment tool we will join A C, A D and A B.
In the Algebra view, note that segment AC is equal to segment AD. They are radii of the circle c.
Now let's measure the angles at the point of contact of the tangents to the circle.
Click on the Angle tool and click on the points B, C, A. and then click on the points A, D, B.
Observe that the angles alpha and beta are 90 degrees.
This is because at the point of contact, tangent to a circle is perpendicular to the radius.
In the Algebra view, click on the arrow triangle named as Toggle Style Bar.
Auxillary Objects, Sort Objects by drop-down and fx drop-down appear.
Click on Sort Objects by drop-down.Sort by menu opens.
This menu has, Dependency, Object Type, Layer and Construction Order check-boxes.
By default, Object Type check-box is selected.
In other operating systems a different check-box may be selected.
Let us select Dependency check-box.
Note that only points A and B are under Free Objects. All other objects are under Dependent Objects.
You can select other check-boxes and see how the objects are sorted.
Now we will learn how to create a check-box.
Click on the Check Box tool and click in the Graphics view.
Check Box to Show/hide Objects dialog box opens.
In the Caption text box, I will type Angles.
From the Select objects drop-down, let us select Angle alpha and Angle beta.
Then click on Apply button in the box.
Angles check-box appears in the Graphics view.
Let us click on Move tool to avoid clicking of other objects in the Graphics view.
Angles check-box is shown as a Boolean Value a in the views.
Using this check-box, we can show or hide the angles alpha and beta.
In the Algebra view, Boolean Value is true when the angles are shown.
Boolean Value becomes false when they are hidden.
Now we will insert an input box.
Click on the Input Box tool and click in the Graphics view.
Input Box appears in the Graphics view.
In the box, type the Caption as Circle.
In the Linked Object drop-down, select circle c. And click on OK button in the box.
Circle input box, along with its coordinates, appears in the Graphics view.
Click on Move tool to select it.
In the input box, type B in place of A and press Enter.
The tangents, angles and all related objects disappear.
Position of the circle has also changed
This happens because all the objects are dependent on point A.
As an assignment, In the circle input box change (A,B) to (B,A) and (A,A) and see what happens. Explain your observation.
Click on Undo button to undo the changes
Now, we will learn how to create a button.
Click on the Button tool and click in the Graphics view.
The Button dialog box opens.
Type Caption as Value.
In GeoGebra Script box type the following script.
Now I will explain the script.
This line will change the position of the coordinates of A to A-1 This means that the x coordinate of A becomes x-1 and y coordinate of A becomes y-l.
Similarly this line will change the poistion of the coordinates of B to B+2.
This line will set the colour of segment j to blue.
This line will set the colour of segment h to green.
This line will set the colour of segment i to red.
Click on the OK button at the bottom.
Value button appears in the Graphics view.
Select the Move tool and Click on value button.
Observe the changes in the Graphics view.
Observe that the coordinates of point A and point B have changed.
The colours of the segments have changed accordingly.
Click on Zoom Out tool and click in the Graphics veiw to zoom out.
I will click the Value button again. Observe the changes in the coordinates of points A and B.
As an assignment, Create a new button. Write a GeoGebra script to change the colour and position of the points A and B.
Now we will combine action tools and see what happens.
I have opened a new GeoGebra window.
Click on the Slider tool and click in the Graphics view.
The Slider dialog box opens.
By default, Number radio button is selected with Name as a. We will leave it as it is.
We will set the Min value to 1, Max to 10 and Increment to 1.
Click on OK button at the bottom. A number slider a appears in the Graphics view.
Now click on Regular Polygon tool and click two points in the Graphics view.
Regular Polygon text box opens. In the Vertices text box, type a and click OK in the box.
Notice in the Algebra view, under Polygon we have poly1 undefined.
As a we drag the slider, notice that polygons with different sides appear.
Now we will insert an input box.
Click on Input Box tool and click in the Graphics view.
Input dailog box opens.
Type the Caption as Number of sides in the box.
Select a=1 in the Linked Object drop-down. Click on OK button in the text box.
Number of sides input box appears in the Graphics view.
In the Algebra view, uncheck the number slider a=1 to hide the slider.
In the Number of sides input box, type 4 and press Enter. You will see a square.
Likewise, you can type any number between 3 to 10 and see the respective polygon.
As an assignment, Create a check box to show and hide the slider and the input box.
Let us summarise. In this tutorial we have learnt about free and dependent objects.
We have also learnt to, Create a check-box Create an insert button Insert an input box
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