Understanding the Circumference of a Circle Formula

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A quick explanation on why the circumference of a circle is 2πr.

[gustavmardby]

Thats not a proof. How do we know that pi equals circumference over diameter in the first place?

[ChandraShekhar-bycd]

Thanks a lot for explaining my childhood doubt finally.. I asked this question and the teacher refused it to answer. But finally I got it here. Please continue with more informative videos. Thanks

[stacyr]

Thanks to you I finally understand the formula. I am your new fan!

[Zxynchronized]

Who else is literally above 12 and still watches this other than me? I'm dumb

[kathika]

When we divide the circumference by the diameter of any circle we get an approximate value 3.14 all the time no matter what is the radius of the circle that is why (circumference/diameter)=pi
Circumference=pi*2r

[madhusudangope]

Great teaching sir.
I am from india.
I love your teaching sir.
Thank you.

[craig]

Thank you... I never understood why a circle was defined as 2pir. I know all the radian measures and the unit circle well, so i know in the case of the unit circle, a full rotation is 2pi, but i never understood why/how the relationship of pi was involved with a circle.. this clears it up

[jannwebb]

You lose me when you have pi = circumference over 2r and you say "finally, solving for the circumference, we can see that it is 2 pi r" Why? You presume I know how to solve this equation: pi = c/2r.

My inclination is to put pi over one on the left side and of course, you already have c over 2r on the right side. So, you should include the step to solve it. You cross multiply, right? *Then* you get c = pi 2 r OR c - 2 pi r.

This is the problem when mathematicians explain things. They leave out one what they think to them is a logical, quick step that doesn't need explaining and you lose your student.

[Aarush-INDIANEXO-L]

for visual explanation, in the formula 2pi*r, imagine the boundary of one half of the circle ( i.e a semicircle), which will be equal to pi*r and when u add it to the other semicircle's boundary which will also be pi*r, we will finally get 2pi*r

[sammyfromsydney]

Congratualtions. All you proved that 2r = D since you started with PI = Circ/D.

[daradaneshvar]

Lmao cheers thx for rearranging an equation for me

[varadarajborkar]

Loved it ☺️☺️
Superb
I was finding for visual videos like these on ur channel
It helped me a lot

[arroz]

So, easy it was but this question was rolling in my head. Thanks for your great teaching. If as a kid I were had learnt the proof so may had easily not forgotten n even if forgotten so my mind were had not rolled the question why if I were had seen this lesson.

[LSMaths]

Nice video Sir Which font is used ? Please reply

[bambangsuyoso]

Many visitor asking about 'how about the proof of pi real value?'

I remember my friend on dormitory was giving me his formula from drawing trigonometry n-place square on early 1999 when he take advanced calculus. I'll write here by words, as comment has no sufficient feature to write detailed formula, hope helps. Here it is,

Pi = lim nto~ of n x sin (180/n),

Use that formula to your scientific calculator will give its value.

[mggamingff]

I really understood after 8yrs this recommended now only

[jacksawhavoc]

gotta agree with karl steinshieber on this one but hey good demonstration of the relationship between pi diameter and circumference

[kms_crs]

cool. I never thought of it that way. I always just thought of it as diameter x pi=circumference. that was really

[zunino]

If Pi is a fractional nuber then we can state that circuncerences "pulses".

[SundeepBorra]

calculation of circumference of circle, has indeed started with manual measurement, from where pi appeared, and hence this doesn't qualify to be a proof of circumference of circle.