Basic geometry: language and labels | Introduction to Euclidean geometry | Geometry | Khan Academy

Before learning any new concept (mathematical or otherwise), it's important we learn and use a common language and label concepts consistently.

Missed the previous lesson?

Geometry on Khan Academy: We are surrounded by space. And that space contains lots of things. And these things have shapes. In geometry we are concerned with the nature of these shapes, how we define them, and what they teach us about the world at large--from math to architecture to biology to astronomy (and everything in between). Learning geometry is about more than just taking your medicine ("It's good for you!"), it's at the core of everything that exists--including you. Having said all that, some of the specific topics we'll cover include angles, intersecting lines, right triangles, perimeter, area, volume, circles, triangles, quadrilaterals, analytic geometry, and geometric constructions. Wow. That's a lot. To summarize: it's difficult to imagine any area of math that is more widely used than geometry.

About Khan Academy: Khan Academy offers practice exercises, instructional videos, and a personalized learning dashboard that empower learners to study at their own pace in and outside of the classroom. We tackle math, science, computer programming, history, art history, economics, and more. Our math missions guide learners from kindergarten to calculus using state-of-the-art, adaptive technology that identifies strengths and learning gaps. We've also partnered with institutions like NASA, The Museum of Modern Art, The California Academy of Sciences, and MIT to offer specialized content.

For free. For everyone. Forever. #YouCanLearnAnything

Subscribe to Khan Academy’s Geometry channel:

[hollypocket]

I love Khan Academy. If I don't understand what my teacher is talking about at school I can come here and look it up. So helpful.

[keeblerelmcookies]

I'm doing geometry now in high school. Failing badly, nothing like this video whatsoever. I blame common core nys for making everything so confusing.

[clodgozon]

The world of science is fascinating. Imagine the world 300 years back then where the society only starts developing and yet, some of the brightest minds invented these formulas that even now, are still useful in our modern world. They are so powerful that revolutionized the world. I love where this is going. Never going to stop learning even after college.

[ruchimukhoty]

Khan academy makes maths a fun learning paradise. I have a maths olympiad after some days and thats when I found khan academy. I have learnt perimeter from here as well. Thank u so much for ur efforts for making such amazing educational videos😊

[kookaburragirl]

Guys to those who think Khan's vids don't help. They do. You just need to actually concentrate on the words khan say. Turn subtitles on they help A LOT

[williamcompitello]

I'm serious on going to college for construction. Geometry will help a ton! This is wholesome info here.

[Budsport_TV]

This just refreshed everything I learned about geometry in Grade School. Crazy what you can get down in a 13 minute YouTube video...

[SGTLeafyGreens]

ive been in Honors Geometry in 9th grade for about 2 months now and ive learned more from you then i have from my own teacher. thanks man

[castboy]

6:19 always makes me laugh. However you are still awesome, these videos always help before a big test :D

[chanceearles]

I started 7th grade and I was very confused about everything, now after watching these videos I feel a hundred times more confident, thank you for making such great videos 😁.

[Sean]

1:53 We could have called this an armadillo 😂
I died from laughing
Also me: I'm not dead if you don’t get puns

[JennyOwnzable]

I LOVE your videos! They are so much help & really teach me like none of my teachers ever could! Thank you!

[somebodyimportant]

My math teacher is on the geometry unit. He doesn't teach us the material and he just gives us a ton of work. This video helped a lot.

[intellectualshutin]

I apoligize for being completely irrelevant, but I was wondering what kind of program you used when you draw all these diagrams? They're really informative, by the way :) They've helped me SO much! :)

[myrobotisgas]

My teacher gives a new concept everyday and expects people to understand. In 45 minutes it’s not enough time to learn completely in a class but thanks to this guy I’m able to learn concepts so thank you

[zachbubbleswhodoesnotsigno]

Thank you for this video. Pass my test bc of it

[nexsusarchon]

he just summed up reality with lines and arrows. *Mind Blow*

[brutal]

I think its sad when I see people criticizing others for thinking geometry is hard. All the different classes Ive taken on geometry have had different ways of teaching it, some much harder than others. Stop putting others down just cause they didnt find geometry as easy as you, the teacher makes the biggest difference.

[salvulcano]

ACT math making me watch the entire geometry playlist the night before. I gotta take the test at 8 am…. ON A SATURDAY!!!

[AnaLeeBR]

thank you so much for this, it's legitimately so helpful to have a video going over basic concepts like these that doesn't condescend to the viewer or automatically assume they are a child