Solved problem - half a pentagon

 


[EN]
Given the figure above, ABD is a right triangle, BE = CE = a, AC = a/2, and CD = CE. The value a is unknown, but it doesn't influence the result. (We can notice that ACEB might be half a pentagon). Find the angle alpha (CDE).

[FR]
Dans le dessin ci-dessus, ABD est un triangle rectangle, BE = CE = a, AC = a/2, et CD = CE. La valeur a est inconnue, mais elle n'influence pas le résultat. (On remarque que ACEB pourrait bien être un demi-pentagone). Trouvez l'angle alpha (CDE).

[RO]
In figura de mai sus, ABD este un triunghi dreptunghic, BE = CE = a, AC = a/2, si CD = CE. Valoarea lui a nu este cunoscuta, dar ea nu influenteaza rezultatul. (Putem remarca faptul ca ACEB seamana cu o jumatate de pentagon). Gasiti valoarea unghiului alfa (CDE).

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Solution / Solutie:

https://youtu.be/hHiVUklQ6ck


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Download the app here | Télécharghez l'appli ici | Descarcati aplicatia de aici:

https://play.google.com/store/apps/details?id=com.solved.geometrycalculator

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