Inscribed angle theorem proof | High School Geometry | High School Math | Khan Academy

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Proving that an inscribed angle is half of a central angle that subtends the same arc. Created by Sal Khan.
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High School Math on Khan Academy: Did you realize that the word "algebra" comes from Arabic (just like "algorithm" and "al jazeera" and "Aladdin")? And what is so great about algebra anyway? This tutorial doesn't explore algebra so much as it introduces the history and ideas that underpin it.
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[@Angel-ggx]

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[@hannahjanz5119]

Angel G if not can

[@okaythenwhatever3573]

Angel G which not witch

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Hahaha!!!!

[@xaimpo]

did it raise to a B?

[@Angel-ggx]

​@@xaimpo That was a comment 8yrs ago bro idk what happend.

[@daviddaasian9685]

As a 7th grader learning advanced math topics alone, it's not always easy to just read instructions in my textbook and fully understand the topic. But, thanks to Khan Academy, I can finally learn without any complications or confusion. Thank you so much!!!

[@papagayin3]

Oh, God, I never understood this at school... You make it look so easy!

[@unknownperson2973]

Thank you our teacher never even taught us this lmao... but its going to be on the test...

[@noelradhakrishnan4423]

😂🔥

[@Tusken42]

Je suis française et je comprends mieux cette leçon que celle dans mon livre !! Merci

[@jizzyq106]

This man really out here drawing straighter lines with a mouse than i ever could with a ruler

[@TheSunMessiah]

the only teacher on youtube which actually helps me pass exams and grading periods...thanks man

[@viaquabee]

oneshot fan detected

[@TPBHvideos]

time to pass my geometry test!

[@CarlosOAO]

did you pass it ?

[@Eng586]

Lol 9 years later sheesh

[@user-sx1ed9oe9t]

@@Eng58612 years later…

[@jetpaq]

honestly ive learned as much algebra as I have geometry in these videos..the whole idea of " prooving.....of "prooooooving" each answer( only you sal heads will get that joke.LOL) , he arms you with an insight thats hard to forget during its application. I really have much respect for his teaching ethic. Assume we know nothing( which is usually true) then show you everything but make it understandable..what a genius.!

[@prestidigitonuim_w.cheese]

this man is my childhood

[@nickambrose50]

love your videos they help me fall asleep thanks

[@iwannacommitjisatsu5858]

Lmao

[@Gonzo01]

You make it so clear. Thanks!

[@ttd972]

If you haven't watched the video yet, pause it at 3:40 and try to solve the rest yourself! It's a fun puzzle

[@sanhitmaity7183]

A very good education platform...

[@ve2zzz]

Excellent teaching !!!! Makes understanding so easy !

[@juanantoniobarragan9536]

Thank you so much for that clear demonstration

[@nayjer2576]

Great and slow explanation, after your explanation of the first case I got the other two.

[@indigobloo7441]

Omg thank you so much i have something due in a few hours and i havent even started

[@judgenap]

Brilliant . understand it now. Thanks .

[@AlexeyYunoshev]

Thanks a lot! It was very helpful

[@browniesnofrownies4843]

I don’t get how si and theta are confusing..???

[@iwannacommitjisatsu5858]

Si=x Theta=y

[@ashvikgarg4913]

i mean like your here aswel

[@JimmyRose1]

8:00 How does the diameter prove that Si equals 1/2 Theta?

[@parikshituniyal]

Theta and si...very intriguing

[@tsukiyakikid8950]

Thanks comrade, Many more students shall pass exams after quarantine thanks to you.

[@caitlincolter4919]

I am sure if I was not so tired this would make more sense. I need a C+ in this class and I am struggling with a F. Guess I will be watching a lot more of your videos.

[@theoyanto]

Very useful thank you, I didn't realise that geometry could be so interesting and informative

[@lixgaze9390]

Really nice video ... our maths teacher uses terms which makes it hard for me to understand thanks to u the concept is clear thank u Khan Academy

[@danielsayre6161]

Thanks for the help.

[@salsadsid]

interesting work.. love you salman .. Great man not ever born.

[@ericcvt]

excellent very theoretical and straight to the poing

[@okaythenwhatever3573]

Life Worth Living yep, straight to the poing and pong

[@SequinBrain]

I've never seen this before. Surprisingly, it never came up in any of the math classes after geometry, which I somehow missed.

[@Anomaly-bv2wn]

this helped thnks

[@henrrymendoza]

Awesome explanation, geometry is beautiful!

[@lydianoronha522]

Yes truly a good helpful one thanks #khans academy

[@oscardarla]

I really hate circles, thank you youtube!

[@jackdudar3982]

thank you Khan

[@joedimon]

Love this proof

[@marekstefanecofficial]

Thanks a lot!

[@Rxhitkhatana]

2010 version of Sal ... op mic btw

[@gopikadas7674]

Ohhhhh this makes soooo much more senseeee

[@freddyyaniga]

can you please just use x and y the si and theta thing is really confusing

[@rashmibhardwaj1328]

freddyyaniga studios true

[@od3stroyer771]

@Just Me lol no

[@kianawhite5793]

Very good....

[@sharljnst]

Very good at explaining

[@Android-jq6wd]

great video

[@ahmedwaly9073]

Amazing

[@hawimohammed6175]

best best best best explanation keep it up

[@abdulshakoor5782]

go nice work sir

[@zuzkhin4472]

About to have a math test in 40 minutes lol

[@fashionablylate7463]

What about with quadrilaterals instead of triangles

[@Th30Hacker]

AWESOME! Best man alive :D

[@okaythenwhatever3573]

Th30Hacker Wait you r dead ;)

[@catmanchester3847]

I would have liked some more real examples, like with numbers and solving for other angles

[@Jaba6798]

Genius

[@moth36]

Nice proof

[@sat2ap329]

good

[@jhonrayplays6881]

what app do you use

[@marchmelendez]

You have awesome handwriting

[@abdulkhadir4498]

My book says same arc which is so confusing!Thanks so much for the subtended arc lmao.

[@bBbKce]

cool bro

[@cameronciarrachi436]

Why do you hate X and Y?

[@NatenguyenYT]

Because My X wont get over me, she keeps saying she's "Sorry" but I blocked her eventually so its all gud.

[@shadybigfan]

should give us numbers with the examples

[@CathyAnneable]

thumbs up for hd

[@franchezcavictorino]

I am confusion???¿¿¿?¿

[@EnvyAbomination]

Wait isn't that angle at 5:03 supposed to be a linear angle too?

[@TakticalTekniq]

subtended...SUBTENDED...S-U-B-TENDED!!! LOL OKAY!!!!

[@okaythenwhatever3573]

Timothy Grant thats why I subbed and I didnt know why

[@maybeluca8027]

the mystery

[@dansp51]

sounds like frank zappa teaching geometry :)

[@JennyBeCool]

What programme do you use when you're drawing?

[@ashvikgarg4913]

it's their own software

[@richardswanson455]

just kidding really well explained. your very articulate

[@MrMohsinkh]

I object sir............. fi 1 ias equal to fi 2 because they share the same chord........... kindly guide me.

[@jibreelahmed6503]

Yes si 1 and si 2 are the same and angles and they have the same arc

[@sullivannix4509]

I still dont get it

[@vhfhdkfzu7317]

Sullivan Nix noooooooo

[@socialelitist4256]

I have my gcse math exam at 27th and I understand a fair chunk of it. Watched the video twice, and I have a few questions: 6:41 if 2 Si equates 1 Beta, and if you take away the two, it equals zero, then why the hell is it half of Beta?! Or is it 0.5 x Beta? I see it recourring a multiple/factor (however you would call it), but shouldn't it be 2? Prominently at 14:02 shouldn't that formula be 2Si = 1Beta? This is messing with what I learnt from school, that a similar example of this, should 1Beta = 2Si, or 1Beta = Si x 2.

[@eyyayy8260]

I know you made this reply 5 years ago, but I had a stroke trying to understand this.

[@drevil37373]

i wanted to make a psi joke but i dePSIded not to

[@okaythenwhatever3573]

drevil37373 I was going to but you PSIched me out

[@TheRealKayTrigga]

💀I wanna make math jokes

[@jeonghanandeunwoosshalalal262]

Wait, what?! This is why I didn't want honors geometry...

[@ahmedalbdairi4388]

i wish there's another way to explain this.

[@roxsobad7]

has any1 told y that u have awesome handwriting?

[@kikachu2036]

I’m just trying to complete an 8 question quiz😃 and i’m tryna to not fail it yk…i’m too stupid for this and tired lmao.

[@shiinamashiro6231]

What if there is another central angle? I don't know what to do :/ there are 2 central angles and 1 inscribed angle in my problem

[@pranavs5998]

i know im 5 years late but lol idk

[@peterphilips5152]

*Not to scale

[@FrankTehTank96]

His voice reminds me of Samuel L Jackson... O.O

[@fazzynone1]

X and y is confusing

[@GndmMkv]

Sal. Even though this video help, it would been better if you state the theroem and postulate.

[@okaythenwhatever3573]

Allen Deng no theorem fam just equations

[@ming9935]

Why do I still not understand…

[@looks8727]

yeah this is way too confusing tbh

[@EileenTaylor1]

oh god, this is 14 minutes

[@okaythenwhatever3573]

Eileen Taylor oh god, a complainer

[@DeanAnderson-dw2vk]

Oh yeah sigma😁😁😁🤣🤣🤣😂😂

[@prafuljadhao3672]

Mahol

[@evibot4718]

WHO'S WATCHING THIS VIDEO IN 2008??????!!!!!!!!!!!!

[@mspaint1615]

+Joseph Green "Uploaded on Mar 18, 2010" its 2019 dammit

[@zahraa-dm7qx]

+fangirlninja lol

[@manasakaguchi]

Me did the whole video: si.... theta.... wait how do your pronounce these... r.I.p x and y

[@Cypeq]

THIRD!

[@grzegorzg447]

ima pretend i understood

[@samkthegamer1017]

im the newest comment here

[@nfspayback1248]

I dont get any of it ughughgughughughhgughguhugh!!!!!!!!!!!!!!!!!!!!!!!! I tried solving the questions yesterday and believe it or not , I spent 6 hours on this and till 12 pm , I rage quit!!!!!!!!!!!!!!!!!!!!

[@EternalShadow1667]

Nfs Payback you prob don’t get the background to it. Never give up, ik exactly what u mean, spent approx 2 days on nested fractions. Its ez now. Just put in the effort.

[@jkgan4952]

Smarrtt

[@miravavillamin1595]

he make it more confusing!!!!

[@jerfersonmatos28]

I think the whole idea is that is you make a triangle from the middle of the circle to two points of the circunference the angle of the triangle in the middle of the circle is gonna be twice of a triangle that take the same two point of the circunference but insted of parting from the middle parting from any place of the circunference. I'm sure nobody understood my explanation 😂

[@priyabridgemohan2250]

Plz stop saying si or thetha or whatever it is it’s confusing

[@truhoes762]

bro MLG

[@SuperSmosh123]

How?

[@fireball221000]

DoritosDew get out

[@nXusGFX]

+DoritosDew this made me lose braincells. im trying to do homework. not helpfull :(

[@SuperSmosh123]

it is

[@sanjitmnty1]

Dear sir se padhana sikh

[@bibi7043]

peen

[@King-wi4zq]

Stop being a nerd and say X and Y or A and B

[@Lucy-hl9qg]

😂video not helpful at all

[@jibreelahmed6503]

Just listen carefully, take notes and try to understand what he is saying with an open mind.

[@diabeticalien3584]

+sammy sammy Actually, yes it is. If you have trouble with this math, he explains it slowly and nicely.

[@Dman82499]

He did make it a little confusing subdividing the angles into random geometrical signs, though

[@aidensaroka7268]

The Si and theta stuff ruins the lesson for me. It makes zero sense, and doesn’t help me learn.

[@dansam5467]

Aiden Saroka 2 Psi and theta are just other names for angles you don't know. It's like substituting the letters x and y that you use to mark unknown values by other arbitrary letters.

[@richardswanson455]

horrible explanation