# Poncelet theorem

Zafar Turakulov shared this question 1 year ago

The ggb-file attached provides an illustration to particular (1-parameter) case of the Poncelet theorem for pentagram. The point Aon the plot can be pulled along the circomference and drag the whole of the construction so that the pentagram remains in- and circumscribed as in the very beginning. This property conserves under changes of the parameter u. The last operation was to remove the rays out from the circumference that I could not complete. I just could not find eraser. My question is, will anybody show me how to do this so that I can continue to compose the complete 3-parameter family?

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Il ne faut surtout pas effacer les droites mais ne pas les afficher

et il faut construire les segments du pentagramme

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That is right, but Geogebra gives only thiskind of tangents. If I follow your recommendatin I lose the main property of the construction I mentioned -- it provides an interactive presentation in which you can change the shape of the internal ellipse and rotate the star so that it always satisfies the condition of the theorem. (Sorry, je ne parle francaise).

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have properties been lost in my file ??? I do not think so ...

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Perhaps you are right, that is why I am looking for help. I am using Geogebra for the first time. I expected to find something like eraser, but could nopt find anything like this. Several months back one student has did this in few minutes? but now I cannot find him. Please, look at his work (attached).

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perfect ? no ? for me yes (but perhaps hide captions eq1 ... a .... via eg right click)

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I said, I am beginner and am trying to do it myself because the entire family is 3-parameter. If you will be so kind as to collaborate we would compose a series of funny toys like this. Please, try another one (attached).

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Merci, I'll try it.

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