Algorithmique du cycle 4 - 3e

Niveau 2 : variables

Exercice 1 : Calculer des aires ou périmètres de figures

Écrire un algorithme qui permet de calculer le périmètre d'un carré.
Le programme doit commencer par demander le côté (dans la variable ), calculer le périmètre dans la variable puis afficher ce résultat.
Par exemple si l'utilisateur rentre la valeur \(9\), le programme doit fournir \(36\) comme résultat.

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Exercice 2 : Déplacement véhicule - Décrémentation de variables (2/5)

Votre véhicule est équipé d'un réservoir contenant 20 litres d'essence, plein au démarrage, et il consomme de l'essence à chaque déplacement.

Nous allons modifier notre compteur pour qu'il diminue à chaque déplacement. Une variable peut être réutilisée pour faire un calcul avec sa valeur. Par exemple le bloc fournit la valeur actuellement mémorisée par la variable soustrait de 1. Combiné avec la balise , il est donc possible de modifier une variable en fonction de sa valeur précédente.

Modifier l'algorithme pour initialiser la variable et diminuer de 1 le niveau d'essence après chaque déplacement d'une case du véhicule.

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Exercice 3 : Utiliser le théorème de Pythagore pour trouver une longeur (niv 3)

Soit ABC un triangle rectangle en A. Ecrire un algorithme capable de calculer la longueur du segment bleu pour les deux cas suivants:
Cas n°1:

Cas n°2:

Votre algorithme doit afficher les mêmes résultats pour les exemples suivants :

pour cas = 1, segment n°1 = 21, segment n°2 = 29 on affiche 20.
pour cas = 1, segment n°1 = 25, segment n°2 = 20 on affiche 15.
pour cas = 2, segment n°1 = 32, segment n°2 = 24 on affiche 40.
pour cas = 2, segment n°1 = 15, segment n°2 = 20 on affiche 25.

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Exercice 4 : Comprendre les variables algorithmiques et mathématiques

Soit \(x\) un nombre réel.
Soit \(total\) un autre nombre réel, correspondant à la valeur renvoyée par l'algorithme.
\(total\) vaut \(x\) plus \(4\) multiplié par \(4\).

Compléter l'algorithme suivant afin qu'il réponde à l'énoncé.

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Si on entre un nombre \(x\) indiquer l'équation donnant \(total\).
Exemple de réponse : \(total = 0,01x + 1\)

Exercice 5 : Déplacement véhicule - Introduction d'une 2eme variable (5/5)

Maintenant que le niveau d'essence fonctionne, nous voulons rajouter un compteur de distance.

Utiliser la variable pour calculer la distance parcourue en la réinitialisant à 0 au démarrage et en l'augmentant de 1 à chaque changement de cases.

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