Insert Images

Cat on ladder. Move the red point!

If you think that it looks dull to let a point represent a cat, you can insert an image of a cat.

Find images

If you don't want to make the images yourself, there are plenty of images on the Internet. Watch the license! Don't do like Lamar Smith, the man behind SOPA, who took an image that was under a Creative Commons Attribution license, without giving any attribute to the creator. Bluntly ignoring the license, like Lamar did, is disrespectful and against the law! And it would not help to remove the site after being caught, your reputation as a law abiding citizen would be ruined for ever.

flickr is a good site for finding photographs, if you click "Advanced" under the search box, you can choose to only search for images that are under a Creative Commons license.

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At Classroom Clipart you can download school-related clipart.

Right-click on the image you want to download and save it to your computer.

Exercise 1 - Insert an image in GeoGebra

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You can use the picture of the cat to the right. Right-click on the image and save it.

Find the tool Insert Image icon in GeoGebra. Click anywhere in the drawing pad to place the image. You can place the image at a point, like a point on the ladder. After clicking on the point, choose an image from your files. You can also drag an image from your computer to the drawing pad of GeoGebra, when doing so, two points are created at corners 1 and 2 of the image.

Exercise 2 - Adjust the position of the image

If the point on the ladder is called C, and if this point is chosen when positioning the cat, the position will be as in the picture to the left.

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You can adjust the position by right-clicking on the image and choose Properties... Then pick the tab Position.

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In the picture above, the lower left corner of the image has been moved -0.7 along the x-axis and -0.3 along the y-axis.

Different layers

If you pick the tab Advanced in the properties window, you can choose a layer for an object.

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Objects in layer 0 are behind all other objects, they might hence be difficult to target when clicking. The objects in the highest layer are at the front of the worksheet.

When it comes to images there is another property for deciding the depth. Under the tab Basic you can check Background Image. In the applet "Cat on Ladder", there are two background images, one depicting bricks and one depicting asphalt and balloons.

Distort the image

By specifying three corners under the tab Advanced, you can distort an image. In the picture below, A is chosen as corner 1, B as corner 2, and C as corner 3.

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If an image is placed by attaching one corner to a point, then the size of the image will not change as you zoom. In order for the size of the image to change, you must attach two (or three) corners to points. To see the difference, zoom in and out in the Cat on Ladder applet above, the cat is only attached to one point but the background images are attached to two.

images from:

Cat Silhouette by OCAL from: http://www.clker.com/clipart-11768.html

Bricks by robpatrick from: http://www.flickr.com/photos/alkalinezoo/192889545/

After party by Bright Tal from: http://www.flickr.com/photos/bright/69687519/

by Malin Christersson under a Creative Commons Attribution-Noncommercial-Share Alike 2.5 Sweden License

www.malinc.se