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Volume of a cone | Perimeter, area, and volume | Geometry | Khan Academy 

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27 окт 2024

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Комментарии : 81   
@variannevo642
@variannevo642 8 лет назад
Thank you so much! This video actually helped me earn an A on my math quiz.
@willywonka2615
@willywonka2615 4 года назад
👍
@footballworld3869
@footballworld3869 7 лет назад
This man his drawing is awsome!
@masonwong895
@masonwong895 5 лет назад
yes it is
@astrq1un3
@astrq1un3 4 года назад
y e s i t i s
@MrMShake
@MrMShake 7 лет назад
Please can you guys make a video to calculate the surface area using integration
@Paradox_Incognito
@Paradox_Incognito 4 года назад
Thank you so much!!! I'm watching your videos over the summer to help remember what I learned this school year
@dorinemorris4667
@dorinemorris4667 4 года назад
This man's drawing is spectacular! :)
@irlallan
@irlallan Год назад
Bro actually explained a 45 min geometry course in 5 mins - like that's insane!
@irlallan
@irlallan Год назад
also who else is in 2023 rn?
@wilhufftarkin8543
@wilhufftarkin8543 2 года назад
One thing that still baffles my mind is, WHY exactly is it 1/3?? If you take a 2D cross-section of a cone within a cylinder, it's basically a rectangle with a triangle within it. You can bisect the triangle into two equivalent mirrored triangles and you get two rectangles that are halved diagonally. If you add all the resulting triangles together, you should get 2/4 or 1/2, not 1/3. Yes, it's not 2D but 3D, which is a whole other story, but if you circle this whole thing around, I still don't understand how you get 1/3, even though it intuitively makes sense.
@lolthehihi929
@lolthehihi929 Год назад
I am also wondering the same thing.
@irlallan
@irlallan Год назад
I'm not sure but I'm pretty sure that we can test it, like try finding a funnel, and then a big cylinder like a water bottle, gallon jug of water etc. Put it inside, then figure out the volume of the cylinder, then the volume of the funnel. It won't be as accurate, but it will give you an idea of how it works. But still, like you said, it intuitively makes sense, though visually, it doesn't. Hope this helps!
@wilhufftarkin8543
@wilhufftarkin8543 Год назад
@@irlallan That's probably how the ancient Greeks did it.
@marcarias5350
@marcarias5350 6 лет назад
oh yes i learned so much!!!!!!!!!!!!
@antonioquadrado734
@antonioquadrado734 8 лет назад
but WHY is the volume of the cone 1/3 of the volume of cylinder?
@kat5607
@kat5607 8 лет назад
if you take 3 cone of same volume melt it and then mold it into a cylinder it will be equal.
@anteconfig5391
@anteconfig5391 7 лет назад
I know right. I need some mathematical proof. So I made some up. I presume that the VOLUME of a cone is the AREA of a triangle times the length of the circumference of the circle created by the cone. sooooo AREA of a triangle (I'll call the base "r") = rh/2 circumference of circle = 2*pi*r when you multiple these together you get 2*pi*r*r*h/2 or h*pi*r^2 for some reason when I crunch the numbers I get TOO MUCH SPACE (???) hmm idk what to do.. So I pretend that the reason I get to much space is because I accounted for "r" twice in the equation OR because the amount of space I have is the volume of a 4 dimensional cone (I'm not sure if that true but....... ...) so I divide by 3 (because Length * Width * Height = the volume of a 3 dimensional object) and get the proper answer. h*pi*r^2 / 3 or 1/3 * h*pi*r^2 In other words... I'm in the same boat as you. I need mathematical proof.
@tamircohen1512
@tamircohen1512 6 лет назад
I'm a year late but there are videos which explain this using calculus. If you're still interested and still don't know check them out.
@andresrebata1958
@andresrebata1958 6 лет назад
its not a rigorous proof but u can think of how in 2d a triangle is half the area of a square with same height and width bc as the hypotenuse reaches the "peak" it loses half the area since its in 2 dimensions. Kind of the same happens with a cone but this time in 3d so as the side reaches the "peak" it loses 1/3 of the area. Hope this helps
@jasonvirasami1444
@jasonvirasami1444 5 лет назад
Neko Master but it looks like 1/2 to me
@sumaysethia7693
@sumaysethia7693 5 лет назад
Nice vid pretty helpful
@itsbillie1968
@itsbillie1968 3 года назад
Helped so much thanks
@-MissSiri-
@-MissSiri- 2 года назад
I WANNA SING YOU HAPPY BIRTHDAY YOUR DRAWINGS AND TEACHING STYLE ARE AMAZING!! ❤️
@aishanasreen464
@aishanasreen464 6 лет назад
Thank you sir.your teaching is very best
@figueroabryan8656
@figueroabryan8656 Год назад
tyvm bro!
@TiberiusStorm
@TiberiusStorm 8 лет назад
I have a Texas Instruments calculator but I had to input it differently than Sal to get that answer. r = √393/(5π)
@husseinsabrie3407
@husseinsabrie3407 6 лет назад
the volume of the cone 1/3 of the volume of cylinder and did you get 5 pi
@thomasdeng7659
@thomasdeng7659 9 лет назад
how did you get that cool calculator?
@chideranwosu211
@chideranwosu211 8 лет назад
It is a Texas Instrumental. You can get it off Amazon
@Aadhyavyasasa
@Aadhyavyasasa 8 лет назад
nice video
@queeniefredabjumalon4615
@queeniefredabjumalon4615 3 года назад
Thank you so much khan academy because I learn advance for your RU-vid and very understanding thanks for all 😊♥️
@vidmaster011
@vidmaster011 5 лет назад
Bro...if I didn’t come across this video in 10th grade I would have dropped out...the formula kept pissing me off. I ended up putting .3 and 1/3 in my calculator and kept giving me dumb answers. I finally put in a 3 and got it right. Phew...
@gaurav.raj.mishra
@gaurav.raj.mishra 5 лет назад
👍
@NoahGoldsmith
@NoahGoldsmith 8 лет назад
The height and radius were the same??
@kat5607
@kat5607 8 лет назад
nope its almost same
@naveenrajg1002
@naveenrajg1002 4 года назад
haven't told about that 1/3? generally people have doubt in this factor.
@bharatpatel6594
@bharatpatel6594 4 года назад
Your welcome
@friendsotsegolakeroute8032
@friendsotsegolakeroute8032 7 лет назад
Another formula is: B x 1/3 x h.
@johnpark1520
@johnpark1520 7 лет назад
friendsotsegolake/ route 80 It's the same formula. Base = pi × r squared.
@m4x970
@m4x970 4 года назад
His handwriting on a pc is better than mine irl
@gainknowledge2999
@gainknowledge2999 3 года назад
How can you take capacity instead of volume?
@kat5607
@kat5607 8 лет назад
correct me if i am wrong. volume of cone could also be area of a cross section of the triangle i.e. !/2*base*height multiplied by 2 pi ?
@astrq1un3
@astrq1un3 4 года назад
Cole Phillips honestly, your an idiotic nosy bully. go away. She/he just wants to actually succeed in life, unlike you.
@dhanvant.p.s6242
@dhanvant.p.s6242 3 года назад
Why can't we calculate the volume by , circumference of the base × area of the right angle triangle = 2πr × rh/2
@galacticcuber2058
@galacticcuber2058 3 года назад
becayse it doesnt staay constant throughout the calculation. In a cylinder, you can multiply the base times the height because the base stays the width throughout the whole shape. In this case, it gets smaller, so you cant have a constant multiplication through the triangle.
@mdzisantanvir9239
@mdzisantanvir9239 2 года назад
@@galacticcuber2058 no he isn't talking about multiplying the circles area with the height, (we do understand that the circular area is decreasing)
@mdzisantanvir9239
@mdzisantanvir9239 2 года назад
Exactly my question, the triangle is moving by the circumference therefore it's only logical that it's (triangle's area x circle's circumference) which would be piR^2h instead they just assume that it's 1/3 part of the cylinder 😬
@onlydreams4328
@onlydreams4328 4 года назад
How did you get 131?
@SFK_CHEESE
@SFK_CHEESE Год назад
Who is this man I goota know
@sangitathapa588
@sangitathapa588 4 года назад
Yes
@mohammedsalih6771
@mohammedsalih6771 3 года назад
It's not clear that the cone is 1/3 of cylinder. No way to be sure. 🤔
@redstallion415
@redstallion415 2 года назад
How/why is dividing by 1/3 the same as multiplying by 3?
@biged680
@biged680 Год назад
because dividing by a fraction does the opposite just like multiplying by a fraction would divide it
@sazidhasansafwan
@sazidhasansafwan Год назад
reciprocal bro
@friendsotsegolakeroute8032
@friendsotsegolakeroute8032 7 лет назад
Because 3 cones fit in one cylinder .
@stellar8689
@stellar8689 7 лет назад
prove it.
@vol230
@vol230 4 года назад
@Charlez Rosa mathematical proof?
@neetu.mishra.
@neetu.mishra. 3 года назад
Not visible
@rikasoft
@rikasoft 8 месяцев назад
Goat
@heshamacademy7396
@heshamacademy7396 6 лет назад
dear salman khan i have a FORMULA to FIND AREA of cone of 2d shape. i m hesham
@aaryama3758
@aaryama3758 4 года назад
HESHAM ACADEMY ddssssss
@havehope646
@havehope646 Год назад
Jesus loves you ❤️
@CrisisMonday
@CrisisMonday 4 года назад
Whenever I try to write on the computer, I get chicken scratch.
@esmeliars
@esmeliars 4 года назад
Hes using a drawing tablet
@Gnerf
@Gnerf 3 года назад
A cone is half the volume of a cylinder
@hollymiller2557
@hollymiller2557 6 лет назад
Heart this comment PLZZZ DUDE we use this at school all of the time
@daniellarson9526
@daniellarson9526 4 года назад
Guys
@kamilavazquez7772
@kamilavazquez7772 9 лет назад
hi
@brendano.2040
@brendano.2040 8 лет назад
+Kamila Vazquez Hello
@bread9418
@bread9418 3 года назад
69 comments Nice
@gaypp6175
@gaypp6175 2 года назад
65
@gaypp6175
@gaypp6175 2 года назад
66
@gaypp6175
@gaypp6175 2 года назад
67
@gaypp6175
@gaypp6175 2 года назад
68
@Chinmoy-Saha
@Chinmoy-Saha 2 года назад
Kire bangir put, eta integration diya korli na kn?
@tye2953
@tye2953 3 года назад
Slow down ffs,
@maadhavsharma4055
@maadhavsharma4055 8 лет назад
good video
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