Le théorème de Pythagore est un outil mathématique très puissant... Show more
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Updated Apr 15, 2026
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Comprendre et Appliquer le Théorème de Pythagore
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Théorème de Pythagore
Le théorème de Pythagore est une règle qui s'applique uniquement aux triangles rectangles. Il nous dit que le carré de l'hypoténuse (le côté opposé à l'angle droit) est égal à la somme des carrés des deux autres côtés.
Dans un triangle rectangle, si l'hypoténuse mesure c et les deux autres côtés mesurent a et b, alors : a² + b² = c².
💡 Ce théorème est super pratique dans la vie quotidienne ! Il nous permet de calculer des distances, de vérifier si des angles sont droits, et même d'aider les constructeurs à bâtir des maisons stables.
L'échelle du peintre
Imagine un peintre qui utilise une échelle de 5m pour atteindre un mur. L'échelle forme un triangle rectangle avec le sol et le mur.
Si le pied de l'échelle est à 3m du mur, à quelle hauteur l'échelle touchera-t-elle le mur? Avec le théorème de Pythagore, on peut écrire : 3² + h² = 5². En calculant, on trouve que h = 4m.
Si le peintre doit atteindre 4,8m de hauteur, il faudra placer l'échelle à seulement 1,4m du mur. C'est facile à calculer avec la formule : d² + 4,8² = 5².
⚠️ Attention ! Pour que ces calculs soient corrects, il faut absolument que le mur et le sol forment un angle droit. Sinon, le théorème de Pythagore ne s'applique pas !
La serre triangulaire
Un jardinier veut construire une serre avec une façade en forme de triangle isocèle (deux côtés égaux). La base mesure 6m et la hauteur 2,5m.
Pour trouver la longueur des deux côtés égaux (AB et AC), on utilise d'abord le fait que le point H est au milieu de la base BC. Donc BH = 3m.
On peut maintenant utiliser le théorème de Pythagore dans le triangle ABH : AB² = AH² + BH² = 2,5² + 3² = 6,25 + 9 = 15,25. Donc AB ≈ 3,9m.
🌱 Dans un triangle isocèle, la hauteur qui part du sommet principal est aussi une médiane et forme un angle droit avec la base. C'est pour ça que le théorème de Pythagore fonctionne ici !
Vérifier si un mur est droit
Un architecte doit vérifier si un mur est bien perpendiculaire au sol. Il marque un point A à 3m du pied du mur et un point B sur le mur à 4m de hauteur.
Si le mur est parfaitement droit, la distance AB devrait être exactement de 5m . C'est comme une version géante du triangle 3-4-5 !
Si l'architecte mesure 5,1m au lieu de 5m, cela signifie que le mur n'est pas parfaitement perpendiculaire au sol. Un petit écart peut sembler insignifiant, mais c'est très important !
🏗️ Un mur qui n'est pas d'aplomb (pas perpendiculaire au sol) peut causer des problèmes de stabilité, rendre difficile l'installation de fenêtres ou de portes, et même enfreindre les règles de construction. La précision, c'est la clé d'une construction solide !
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Where can I download the Knowunity app?
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4.7/5
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The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
Comprendre et Appliquer le Théorème de Pythagore
Le théorème de Pythagore est un outil mathématique très puissant qui nous aide à calculer les distances dans les triangles rectangles. Tu vas découvrir comment ce théorème s'applique dans des situations concrètes comme positionner une échelle, construire une serre, ou... Show more
Théorème de Pythagore
Le théorème de Pythagore est une règle qui s'applique uniquement aux triangles rectangles. Il nous dit que le carré de l'hypoténuse (le côté opposé à l'angle droit) est égal à la somme des carrés des deux autres côtés.
Dans un triangle rectangle, si l'hypoténuse mesure c et les deux autres côtés mesurent a et b, alors : a² + b² = c².
💡 Ce théorème est super pratique dans la vie quotidienne ! Il nous permet de calculer des distances, de vérifier si des angles sont droits, et même d'aider les constructeurs à bâtir des maisons stables.
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
L'échelle du peintre
Imagine un peintre qui utilise une échelle de 5m pour atteindre un mur. L'échelle forme un triangle rectangle avec le sol et le mur.
Si le pied de l'échelle est à 3m du mur, à quelle hauteur l'échelle touchera-t-elle le mur? Avec le théorème de Pythagore, on peut écrire : 3² + h² = 5². En calculant, on trouve que h = 4m.
Si le peintre doit atteindre 4,8m de hauteur, il faudra placer l'échelle à seulement 1,4m du mur. C'est facile à calculer avec la formule : d² + 4,8² = 5².
⚠️ Attention ! Pour que ces calculs soient corrects, il faut absolument que le mur et le sol forment un angle droit. Sinon, le théorème de Pythagore ne s'applique pas !
Sign up to see the contentIt's free!
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La serre triangulaire
Un jardinier veut construire une serre avec une façade en forme de triangle isocèle (deux côtés égaux). La base mesure 6m et la hauteur 2,5m.
Pour trouver la longueur des deux côtés égaux (AB et AC), on utilise d'abord le fait que le point H est au milieu de la base BC. Donc BH = 3m.
On peut maintenant utiliser le théorème de Pythagore dans le triangle ABH : AB² = AH² + BH² = 2,5² + 3² = 6,25 + 9 = 15,25. Donc AB ≈ 3,9m.
🌱 Dans un triangle isocèle, la hauteur qui part du sommet principal est aussi une médiane et forme un angle droit avec la base. C'est pour ça que le théorème de Pythagore fonctionne ici !
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Vérifier si un mur est droit
Un architecte doit vérifier si un mur est bien perpendiculaire au sol. Il marque un point A à 3m du pied du mur et un point B sur le mur à 4m de hauteur.
Si le mur est parfaitement droit, la distance AB devrait être exactement de 5m . C'est comme une version géante du triangle 3-4-5 !
Si l'architecte mesure 5,1m au lieu de 5m, cela signifie que le mur n'est pas parfaitement perpendiculaire au sol. Un petit écart peut sembler insignifiant, mais c'est très important !
🏗️ Un mur qui n'est pas d'aplomb (pas perpendiculaire au sol) peut causer des problèmes de stabilité, rendre difficile l'installation de fenêtres ou de portes, et même enfreindre les règles de construction. La précision, c'est la clé d'une construction solide !
Sign up to see the contentIt's free!
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Sign up to see the contentIt's free!
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Improve your grades
Join milions of students
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
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4.6/5
App Store
4.7/5
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user