Proof of the cosine rule

How to prove the cosine rule using a geometric argument.

[@NomthandazoAmaraSithole]

,my teacher's method was so long and confusing,Thank you soooo much ,You are the best!

[@CamMathsTutor]

Really nice and simple, love it!🙂 Keep up the good work

[@thalithanemutudi]

Where were you when I thought the cosine rule rule was hard to prove ?😭
Thank you so much sir , this was soo easy to understand ❤

[@mrteiijr]

Your explanation is so easy to understand. Thank you very much for the video.

[@SeegalMasterPlayz]

This was interesting to know about. Thanks for sharing the proof with us.

[@masashibata8895]

The proof presupposes Pythagoras theorem which is a special case of the law of cosines, making it somewhat a circular argument. There is a proof without using Pythagoras theorem from more basic principles of Euclidean geometry.

[@thecinedrone]

hmm but you don't use this cosine rule to prove Pythagoras' theorem so it's not really circular right?

[@254screen]

Interesting mehn😮

[@theoremus]

Nice proof, thank you.

[@jennife._rr]

Thank youu🌟❤️!

[@MenLette]

Hi I have a question, why do you subtract equation 1 and 2 together apart from trying to get rid of h^2. How does it make actual conceptual sense, what is it showing exactly?

[@mybigbeak]

if a = b and c = d then a - c = b - d because a and b are equal, and so are c and d

[@eipimath]

Thanks for sharing! I posted a short video on deriving the law of cosines, It should apply for all angles (acute, obtuse, reflex, negative). Hope to get your thoughts.

[@rupom_1670]

Thanks alot i needed this

[@SibuMakhunga]

this was super helpful!

[@ap3xmath123]

Thanks for the proof... I never really found interest in the actually proof after I was thought when and where it was applied... thanks cheers mate

[@lwazisithole4974]

Thanks Sir 🙌💯

[@lexy5959]

Thank you so much

[@nothin_]

The best. Thankyou!

[@dr.rahulgupta7573]

Why you have not put h^2=b^2--x^2 in eqn 2? This directly gives the required result which you want .make steps simple.

[@KapidhwajSonithB]

Bro, subtracting eq.2 from eq.1 is the same task what you are talking about...

[@sakshimishra6380]

Dhanyawad

[@deanambrose2399]

Thanks You Alive My Problem

[@senarnold7]

Thanks so much

[@ibadahmed4984]

Thanks!

[@kamalbabu324]

Super

[@michaellaw8401]

For the first time i see hope

[@hornet-e9g]

wow amazing

[@newengine556]

Why it's 2ac then Change to -2ac

[@logielleEntiopya]

There was a minus sign before the brackets

[@محمدالضيفي-ق1ط]

رائع

[@brycehaigh8877]

It’s pronounced ach not hach