The dot product

[PRANJYOTI100]

Better than coaching classes cofortly sitting infront of pc and learning this holy stuff thanks alot M.R. G.E.N.I.U.S :)

[dan4boi]

Thank you sir, I truly appreciate the effort you've put into these videos.

You're making my revision alot easier!

[davidnhc7]

You talked in circles for the first 5 minutes..

[yamenhawit]

What if we are not given the angle, but the two vectors in terms of i, j, and k?

[Bera1989]

Awesome! I am very thankful!

[ericp3371]

I love how people get so upset over Elzelgator! It's hilarious! He's just some dumb kid... just ignore him. He's already made himself look like a complete douche anyway!

@kckdude2: Love that quote my man!

[TheDJJProductionInc]

DirectX Tutorials WOOT WOOT

[kckdude2]

I can't remember exactly who said this, but a wise person once said: A moron explains the simplest things in the most complicated way; a genius explains the most complex things in the simplest way. Khan is a genius!

[shjh69fgx]

cos (60) = 0.5 man

anywayz thanks alot 

[sami123110]

Elzeltor ur a stupid

[Elzelgator]

@sami123110 i dont have to prove smting to you but belive me i am clever than you...

[Elzelgator]

he is a not a genious. in turkey we all learn this in the highschool lol he is a normal man lol..

[WhutsWhat]

@Elzelgator Well you know what? Although you guys are taught this in high school, it surely isn't "all" of you who understand what you are taught. What makes this man a genius is not because he knows how to do the dot product, but rather because of his capacity to really TEACH it in a matter of minutes, in a way that ANYONE can understand + he even has TONS of other videos about TONS of other topics, that are also explained in an effective way.

[Elzelgator]

@WhutsWhat you have to be kidding me... do you think this is good teaching lol...let me tell you something. in our country thre is lot better teachers... and they are in every school. and also lot of theacher wait for some to employe them... what ever...

and also with my teachers ability i found a formul to find out length of a point.

if you want me tell it ican tell it to you and everyone in your school can envy you...

reply it if you want me to tell you

[WhutsWhat]

@Elzelgator your credibility is rather questionable, since you (most likely) haven't compared every teacher from your country to every teacher in America before making such a broad statement.

...and yes, I'd like to know what the ''secret'' formula is.

[Statty89]

@Elzelgator You are a dick.

[Elzelgator]

@Statty89 you to asshole apaçi

[lpbug]

@Elzelgator a point doesn't have length, it is defined as an infinitely small area in space. So go tell your teacher to go back to 6th grade geometry.

[Elzelgator]

@lpbug that is a poin and it has lenght which is ''0'' you asshole

also that is the proof which prove that dyt hasnt got a lenght so

you can not make part of line with duts

it means that basic maths are wrong

[lpbug]

@Elzelgator Ok, I'm an asshole because I'm telling you that 0 means there is no length. If there are 0 idiots in the world then there will be no idiots in the world. You don't need an equation to prove that, because your mere existence already does. And I did not understand the second part of your argument, apparently your great teachers in Turkey aren't that great after all if you can't even argue with correct syntax and spelling.

[Elzelgator]

@lpbug first of all i am glad to hear that you accept being asshole.

second of all think about 2 lines. which intersect with each other.

they share the same point(dut) with each other huh?

let me go on..

every line made by atoms which has a lot of space between them. so how can you say lines are intersect with each other.

they can not intersect at a point. we are learning like that but experts not doing it like that.

also dot lenght is ''0'' means that you cant create lines with ''0''

[lpbug]

@Elzelgator So what exactly is your argument here then? I agree that every line made by atoms has a lot of space between them but what does that have to do with anything on this video?

[Elzelgator]

@WhutsWhat let me tell you think about a triangle. you can calculate the length of it if you know the angles, (with cosine theorem..)

am i right then let me move on now i want you to decrease one angle of the triangle. i want you to make that angle as 0' ok?

now you have a line. am i right , ok now use the cosine theorem. lets call lengt of that line as ''a'' and the length of a point will be ''x''

x.x = a.a + a.a - 2 .cos0.a.a

x.x = (a - a) . (a - a) this is a simple explanation

[dedly13]

@WhutsWhat you missed the best part! he wants to help and be amazing for FREE!!!!!!!!!!!

[tkatiqah]

wished you were more straightforward like patrickJMT

[ny1fanta]

@tkatiqah yet, you understand the theories behind each steps. this is what calculus all about, math is not all about calculation, is more about theory

[flyhalfinoz]

Sal, kau memang terbaik!! (google translate it =D )

[akshan1844]

Thank you Sal:)

[jabberwiki]

cosine of 60 degress is 1/2

[Candorly]

4:46-4:53 It clicked in my head. :D

[anisotropicentity]

hey sal cosine of 60 deg is 1/2

[KGSultan]

how come you don't have a video on 3d coordinate systems?

[Aggie98bqn]

thanks for the vid.

[natlustafis]

just amazing!....i feel at peace now :)...it all make sense!....its so beautiful wen it make sense...

[gangstafreshmanboy]

ohhhh so thats what this is used for? cross product is easier in my opinion but to each their own.

[Superegio42]

sin60=3^(.5)/2 and cos60=1/2

Just a tiny slip of the tongue from our boy, Sal.

Don't tell him or he will divide by zero and all hell will break loose.

[darkj3am]

you can draw straight lines with a mouse??

[anuragsahoo94]

Just amazing. i liked how you applied it to physics. :)

[axepuzzle]

this is brilliant! wow... thank you so much :D

[haplocanthesaur]

cos(60) = 1/2

[ana8woahhh]

COS(60)= 1/2

[FurlowFurlow]

Thanks helped out great, this very simple principle that was never explained and expected to be known at the start of my engineering of electronics course. I was confused totally because I didn't know why we had to do cross and dot product.

[rbraves8]

cosine 60 is 1/2

[MrBlenderMan]

@rbraves8

which is the sqrt of 3/2. :o

[jijorit]

in what situation the scientist gone to think about dot product?what is the nessecity of dot product?what is the inspiration behind this?

[axepuzzle]

@jijorit he explained that.

[tobsmonster2]

Great video, thanks

[TheHassanSoomro]

Nice

[rups2k7]

go hd. and buy yourself a table. i think it would look wonderfull

[twll91]

that was great - thanks!

cleared up shit my phys prof made confusing as hell.

[bry1012777]

Hey Sal you videos are very helpful, but in this video you said and use the COS for 60 degrees is the square root of 3/2. The COS of 60 degrees is actually 1/2. Thanks again

[RamirezHD]

king of you tube! thanks

[MetalMario0416]

Excellent!

[surkhaabb]

dude, one word. leeeegendddd!!

thankz a lottt :)

[WadeWiinikainen]

50 Free Youtube Subs Here watch?v=uD5Zi4ZGLhM

[QuantumCoulomb]

Awesome explanation!!

[QuantumCoulomb]

so happy i found this!!

[jesuslover037]

Sal, you're awesome! Thanks so much for your help.

[TDAWizard]

isn't cos(60) 1/2?

[robutubin]

@TDAWizard Yes, thats y his answer was off.

[FirmStool]

gw mate.

[KevinSingh1986]

Great tutorial! The best explanation of the dot product that I've seen yet. Great attitude and enthusiasm definitely help.

[rinwhr]

Wait, isn't cos60 = 0.5??? sin60 is sqrt(3)/2

[darkknightgaury]

cos60=1/2

[dewi20]

thanks man

[KhalidAlmaktoum]

Thanks was wondering why the formula for the dot product was like that.

[presley64]

it really makes sense the word, projection you used.This is the important point. Completely Agree with you-

[Satanic1992]

yeah cos60° is ½ but it doesn't matter, what matters is the concept

[trulymagician]

distance=scalar quantity

displacement= vector quantity

[VonNemo19]

distance is not a vector quantity.

[Peterr86]

@VonNemo19

straight line: distance and displacment are equal

[avinashofphoenix]

@VonNemo19 According to the formula its

Work = Force x Displacement x cos x ....

He just means that to be displacement and it is a vector Quantity...

[tlast2012dude]

best video about dot product on youtube.

[YoniZimm]

Hi there I am a science teacher and I am expanding my background and certifications to physics. This has been an amazing review! Thank you so much for these videos

[CYGNUS609]

hi....I am electrical engineer I also watch these videos to refresh my basics...very absorbing and smooth teaching...easy to understand ....keep it up....1000 times better than books

[TheMrHandyMan]

Here is another quick video of how Dot Products can be used in the engineering world. Thanks Sal.

[DannyAces]

Holy crap you're so helpful!

I must have reread my textbook fifty times and come up blank but in 10 minutes it became so clear and easy!

Thanks

[astroblogger]

cos(60 degrees) = 0.5

[juraad]

yeah, you did sine instead of cosine ;-)

[BKJAGS]

These videos are honestly the best out there. They have helped clear up, review, and teach me how to do math and physics. Had i known about the other series Sal has made I would have watched them too. This is an invaluable resource to those who need any kind of help, thank you very much for your time and effort Sal!

[ollieoniel]

good video

[ose90]

thanks sal, you are a genius!

[kanzie88]

just an advice should have had that vector pulling the cube be pointing towards the ice so that the cube will be lifted

[aubreydavid]

yall got some nerve in here giving Sal advice and bad mouthin. I know his teaching methods are effective because they have really helped me. keep it up my boy, you're Great

[99boy]

what? kanzie was just giving advice.. why is everybody hating on him

[couscousable]

@aubreydavid I understand what message you are trying to send and I partially agree with you. I myself am a fan of Sal. But as far as giving advice or sharing one's opinion is concerned, I think everyone should be able to express their own views and suggest proper corrections if necessary as long as they do it with utter respect. Even the greatest of minds make mistakes. Cheers!

[tigernov6]

cos 60 = sin 30 = 1/2

[rosalindjeans]

you ramble too much and more time than necessary.

[hakoboy70]

i think cos(60) is

1/2 so work should be just 500 J

...

[DanRYoung]

Methinks you're right. I don't blame him -- I always get my 30 and 60 degree exact measures screwed up.

[hakoboy70]

haha... ya i still have to draw the darn circle

[MyOverflow]

"Just basic Calculus"

I never thought I'd ever hear that line.

[1a1a2a3a]

lmao.. .same

[serahtan]

THAT WAS SOO HELPFUL!

Thanks a bunch! :)

[Godson2O]

Excellent Video 10000000/5.

[muddwell]

its only out of 1000000 .. jeez

[dolanpsp]

woah, you are amazing, our teacher could not explain it, and you did an amazing explanation

[geminiflux0]

you are amazing

[jplonmars]

THANK YOU SOO MUCH for the lecture. neither my book or my instructor proved this in the class so I was sooo confused. you cleared it all up for me . Thanks!

[benzi455]

Hi, great video. I really like what you're doing. Two little mistakes I noticed though:

"Multiplication's associative, you can switch the order" -- you mean commutative

cos 60deg = 1/2 (not sqrt(3)/2)

But thanks so much for taking the time to make all these videos.

[Nanumir]

how did you make these videos? did you write with a mouse the whole time, thats hard to do lol?

[danielgirotto]

he probably uses a drawing tablet

[Aliuar]

I'm building a game engine, and I love this :)

[pud]

Thank you!

And for all you kids who think you'll never need this knowledge in the "real world" -- I do right now and I'm 33. Wish I'd paid more attention in high school. :)

[safithegr8]

thanks dude...i'm in 11th grade and your illustrations are really very helpful....thanks alot man..

[petermetric0]

Its good and nicely presented but you do not prove the formula and you do not explain why (a dot b) has dimensions of area. A projection would have dimension length. I think the true representation of (a dot b) is an area, not a projection. Once this is done the linearity, symmetry properties and cartesian formula follow naturally.

[pacda599]

Thanks, Very helpful!

[90redgst]

Great explanation But the Cosine(PI/3) Is 1/2.

[shim2dawg]

great job

good use of colour.