Law of cosines | Trig identities and examples | Trigonometry | Khan Academy

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[@Jacks.Outback]

Son: Hey Dad, why is my sisters name Rose? Dad: Because your mother loves Roses. Son: Oh ok thanks Dad Dad: No problem, Law of cosines | Trig identities and examples | Trigonometry | Khan Academy

[@KanekiSidibe]

you deserve a like for this

[@katzomatzo7448]

lmao

[@crow2533]

This is a life saver bc I’m forgetting everything during quarantine.

[@borca3052]

Loooooool so true

[@kaydenbb2705]

Same

[@strawberrv2017]

Kayden Bb same

[@lawsonsantoro5361]

Yes all of the “IMPORTANT” stuff yes

[@albertjackinson]

I'm just learning new stuff here. Math is fun.

[@davidkhamush2801]

This 4 min video saved me a half hour of listening to my teacher’s lecture. Thanks Mr Khan!

[@robertharris2139]

Khan Academy = Advanced Tech Support

[@rohaanthawizard3120]

what a bad joke..

[@jess6241]

Moe Khan your life is a bad joke

[@AtticAnatomy]

I got 14.6 without having to type in cos87 at all! Is this possible?

[@elorasimonson7354]

omg I'm glad I found this, my teacher won't teach properly to the online students so I have had to teach myself

[@TrioArtsOfficial]

I have a test today on this but now I think I’ll pass it

[@angie8110]

My test is in two days 😥

[@giogainz]

Mines tomorrow

[@Daazle]

Tmr 😕

[@johnedjeba9616]

Mine is tomorrow 10 :00am

[@OayxYT]

so how did the test go?

[@nathalieroberts1565]

Thank you so much for explaining this problem!!! :)

[@jeromecolico1960]

I really appreciate your kindness and effort sal khan. :D you're the reason I got high grades

[@madelinechambers1918]

Thank you so much. This video helped a lot!

[@cobyup10]

You don't have to hit the "times" key before the function key. It's built into the circuitry. So you can just punch in, for example, 2sin(45) or 3cos(60). Saves keystrokes. Also, I just go straight to square root when solving for a side and straight to arccos when solving for an angle.

[@JapanesePiano1]

He is trying to illustrate it to avoid confusion.

[@zen3671]

Thank you so much for your help 👍🏽

[@justjesss9051]

Thank you have really helped me

[@Jeonify_]

I love ur videos soo much, they help me soo much Thank you

[@Slinqee]

ily khan

[@gabeoverbeek1553]

Khan academy always come in clutch

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TY SOO MUCH MAN!

[@2oqh]

thank you very much

[@connerposter9422]

Thanks Khan

[@raejohnson2647]

Thank you!

[@badomens2906]

A true American hero

[@emilyyyyyyyyyyyyyy.y]

thank youuu

[@atoz7139]

Life saver...

[@lorenmerluzzo]

Thanks

[@caden4545]

thank allah for this video

[@sulhogar]

what program are you using to write things down?

[@verymuchscience1800]

+sulhogar I know this comment is a year old, but its "smooth draw 4"

[@sheardown]

I know this comment is a year old, but thanks

[@jorgetadeo510]

Thanks and I know this comment is 2 months old

[@jerfersonmatos28]

J T I know this comment is 4 months old but I don't know what to say

[@SteroidChicken]

lol this comment is one week old Im just tryna point that out

[@patzer7263]

How about if C side is missing Do i still use the A²= B²+C²-2BC (CosA) ??

[@willthegirl]

C²=A²+B²-2AB(Cos c)

[@smellthel]

thanc

[@lenkastranjakovic261]

Can we do this by this method, i worked a little bit around angle ration and end up with this formula a = sin(b/(b+c)*theta)*b+sin(c/(b+c)*theta)*c and got identical answer ?! And what this this method is called if it exist?

[@taitgrahan9350]

Litteraly saved me from a test tomorrow

[@tomvo7990]

What’s the math teacher’s favourite food Me: Coleslaw =))

[@k-l7204]

I kinda think I get it

[@verymuchscience1800]

sal i love you so much thank you i love you so much

[@cobyup10]

It's easier to see if you call it angle A, which is opposite side a.

[@kenguo1357]

me coming from the video 12 years ago with pixel quality

[@alexkim3084]

His voice is so low😂

[@mariarahelvarnhagen2729]

It's Trivial To Estimate CA From AB Perspective

[@derekmontgomery6237]

Khan academy has passed me from 5th grade to tenth grade

[@gamefreaker54]

What do you do if youre looking for one of the angles?

[@devmehta5313]

Maybe the inverse?

[@xjohnx5672]

isolate the cos angle in the standard equation and solve

[@TehSainty]

Roger Valencia You'd just rearrange the cosine rule, so It would be COSA= (-a^2 +b^2 + c^2)/2

[@umarshifas3662]

or cos(A)=(b squared + c squared - a squared)/2bc

[@jerfersonmatos28]

Once I've tried to solve a triangle with the cosine law, and I got a quadratic equation, but what is the answer, the x¹ or the x² ?

[@karthikpurush4661]

Jerferson de Matos well that's most likely incorrect ma dud

[@ferlynjoycorriente639]

Then... to find the other angles... it is law of sine next, right?

[@moustafagebal5366]

Please please what is the name of the app that you use to draw?

[@kat_064]

Thanks!

[@supermerk1443]

B would be c bc a2+b2=c2

[@ruthfrancisco3984]

how did you get the 144 and 81? please reply me ASAP

[@jt26515]

The Squares of b=12 and c=9 (i.e. b^2 = 12^2 = 144)

[@christ4u2now]

@@jt26515 Sorry for asking stupid things, but why do you write 12^2 instead of 12x2. Is it more accurate to write that way in algebra?

[@connerdiamond6165]

Anyone fall asleep in class and gotta learn it

[@wolfteef]

yep and i have a test next hour 😌✨

[@engraedrazzaq7067]

As possible to solve( cosA=b'2+c'2-a'2 /2bc ) by method partial Derivative

[@adhritgulati6794]

That just sounds like the Pythagoras theorem but with extra steps

[@mercilessanim]

It is, but this is useful because Pythagorean theorem only works for 90 degree triangles.

[@GermanSnipe14]

*your

[@sarahj5032]

can you but Arabic translation. it's well helpfull to understand

[@wellhellothere9841]

I didn't learn it this way uhh

[@wilminahokulani]

how did u get 87 degrees?

[@jerfersonmatos28]

For those who have the same question he just set it to be 87.

[@Jacks.Outback]

It was given to hi,

[@cullenwilliams1695]

Given

[@vexrow378]

What grade education is this

[@dreamzplays4453]

I'm taking this in grade 10

[@cvckw]

Grade 11 for me

[@lowercaseletters_]

Grade 11 for me, some for 12.

[@elliesuzuki4688]

I'm taking it this year and im in 9th grade.

[@nonja]

I took it in 8th, really depends what school you go to

[@omarrybarry2358]

hamburbers

[@ahmedkepil1073]

this is wrong u dont put it straight into your calculator u have to work out each side seperately and then you put it in your calculator. this video confused me a lot during a question i was doing

[@FirstnameLastname-ni9uh]

At this situation the easiest would be pythagreom theoram

[@jerfersonmatos28]

Sterling Archer Pythagorean theorem only for right triangles. And a right riangle is when it has a 90° angle, that is a straight horizontal line and a straight vertical line

[@thesimplemindofazeez109]

ly no homo

[@nexlexx]

his voice lowkey hot...

[@theolumy8627]

lol

[@arnav3929]

I am just writing it so anyone likes on it, i can return to this video n revise it lol