# Différences entre versions de « Tutoriel:Insérer Images »

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## Drawing Tool for Symmetric Figures

Open the dynamic worksheet Drawing Tool Symmetry. Follow the directions on the worksheet and experience how your students could explore the axes of symmetry of a flower.

Hint: You will learn how to create such dynamic worksheets later in this workshop.

• How could your students benefit from this prepared construction?
• Which tools were used in order to create the dynamic figure?

### Construction Steps

 1 New point A 2 Show the label of point A 3 Line of reflection through two points 4 Mirror point at line to get image A' 5 Segment between point A and its image A' 6 Turn the Trace on for points A and A' Hint: Right click (MacOS: Ctrl + click) the point and select Trace on from the menu. Whenever point A is moved it leaves a trace in the Graphique. 7 Move point A to draw a dynamic figure

### Discussion

The Trace on feature has some special characteristics:

• The trace is a temporary phenomenon. Whenever the graphics are refreshed, the trace disappears.
• The trace can’t be saved and is not shown in the Algèbre.
• To delete the trace you need to refresh the views (menu View – Refresh Views or key combination Ctrl + F. MacOS: Open Apple + F).

### Enhancing the Construction

Note : Make sure you have the picture A13_flower.jpg saved on your computer.
 8 Insert image into the graphics view Hint: Click in the lower left corner of the graphics view to insert the picture at this position. 9 Adjust the position of the inserted image. 10 Set the image as background image (Properties dialog, tab Basic). 11 Reduce the filling of the image (Properties dialog, tab Style). Hint: After specifying the picture as a background image you need to open the Dialogue Propriétés using the Menu Éditer. You can’t select a background image in the Graphique any more.

## Resizing and Reflecting a Picture

In this activity you will learn how to resize an inserted picture to a certain size and how to apply transformations to the picture in GeoGebra.

### Construction Steps

 1 Insert picture A14_Sunset_Palmtrees.jpg on the left part of the [[Graphique ]] 2 New point A at the lower left corner of the picture 3 Set point A as the first corner point of your picture. Hint: Open the Properties Dialog and select the picture in the list of objects. Click on tab Position and select point A from the dropdown list next to Corner 1. 4 B = A + (3, 0) 5 Set point B as the second corner point of the picture. Hint: You just changed the width of the picture to 3 cm. 6 Vertical line through two points in the middle of the graphics Vertical line through two points in the middle of the Graphique 7 Mirror the picture at the line Hint: You might want to reduce the filling of the image in order to be able to better distinguish it from the original.

1. Move point A with the mouse. How does this affect the picture?
2. Move the picture with the mouse and observe how this affects its image.
3. Move the line of reflection by dragging the two points with the mouse. How does this affect the image?

## Distorting a Picture

In this activity you will learn how to resize an inserted picture to an arbitrary size and how to distort a picture in GeoGebra. You will now modify the construction created before. If you want to keep the original as well, you need to save your file.

### Construction Steps

 1 Start with the figure you created in Resizing and Reflecting a Picture 2 Delete the point B to restore the picture’s original size 3 Create a new point B at the lower right corner of the original picture 4 Set the new point B as the second corner point of your picture. Hint: You can now resize the image by moving point B. 5 Create a new point E at the upper left corner of the original picture 6 Set the new point E as the fourth corner point of your picture

1. How does moving point E affect the picture and its image?
2. Which geometric shape do the picture and the image form at any time?

## Exploring Properties of Reflection

In this activity you will create a dynamic figure that allows your students to explore the properties of reflection. You will now modify the construction created before. If you want to keep the original as well you need to save your file.

### Construction Steps

 1 Start with the figure you created in Distorting a Picture 2 Segment between points A and B 3 Segment between points A and E 4 Parallel line to segment AB through point E 5 Parallel line to segment AE through point B 6 Intersect the two lines to get intersection point F 7 Hide auxiliary objects 8 Reflect all four corner points at the line to get their images 9 Connect corresponding points with segments (e.g. points A and A') 10 Create angles between the line of reflection and the segments