Mathematical Proofs: The Cosine Rule

[DinoKicker]

1:42 lol@BAD triangle

[claudilicious6]

God Bless you old man.

[xxbcmbiggestfanxx]

now why can't my teacher explain it like that?? thanks, great video!

[eMBLAQ]

Thankyou! It was wonderfully explained and very easy to follow.

[whatever534231]

absolutely brilliant, thankyou thankyou thankyou :)

[chimera66]

This is the best and most simplest way of proving the law. Excellent work!

[chimera66]

Orange, lemon and ultra violet. Thank you.

[Forry2087]

you are a genius mate! good work

[meterotronic]

my intuition thanks you

[meterotronic]

The best proof yet...better than that "Khan dude....peace be with you

[leoisrael223]

MAAAN SO COOL, THIS IS AN AWESOME PROOF!!

[mountpeaceboy]

you lost me why didn't you just call b-x ... y? that would be less confusing

[allstargrimemusic]

excellent video & well explained :-)

[lazer1235]

absolutely <3 your accent ahaha 'pythag-oras the-orum' and "substitute it in the equa-zion" xD

[cookiesncream926]

thank you so much! now i have a chance at passing my math test tomorrow!

[SebAlva]

4:37 mindblown

[frostwow]

only half of a success. because drawing a unitcircle over the angle A would have proven useful.

and also exploring this case with what if we draw the line h from angle C, wouldve been interesting

but thanks anyway

[sweentnhot0104]

@frostwow even though you draw h from angle c, or whatever other angles, it doesn't matter.

[Zelphii]

this is the best video ever.

[4realsucka]

Thank you so much!!! This video deserves 1,000,000 views haaaaa

[warsilver99]

Thanks a bunch, really helped me out..

[Youdontwantmyusernam]

THANK YOU! maths homework Done!

[MrPlender]

Brilliant! Short and simple. Thank you very much.

[ThomasMR1]

haaaaaaaaaaaaaaaaaaapppppppppp­pyyyyyy!

[jamduke]

So you equate the two right angled triangle's pythagoras theorems to remove h, and use cosine to remove x. Thanks!

[roarmaster2]

5,461 people have watched this video and growing

[roarmaster2]

@roarmaster2

i finished watching the video and it grew to 5,466

[akyra83]

Beautifully explained :), im so happy i can cry. Thank you so much!!!!

[monsieurhari]

Thanks A LOT!!!!!!

[note4mark]

Very well done!

[treemantris]

Great video, thanks

[burhanuddin10]

really helpful...thanks

[freesizepile]

So lucid !

[leestone8]

that was really helpful thanks

[OL1V3R666]

Explained really well! Should definitely help with my Oxford Maths Entrance Exam! Cheers!

[snaguey]

A nice proof thank you!

[britecho]

Using his triangle you can write h/c = Sin A and h/a = Sin C. Thus we can write, h=c Sin A and h=a Sin C. Or, c Sin A = a Sin C. This can be rewritten in the familiar form a/Sin A = c/Sin C. Hope that helps.

[Yu2Kal]

@britecho and to get the other part frop the perpendicular in a different direction

[MickyJimbo]

Thank you, helped out a lot!

[welshboyomon]

Great Video, very helpful thanks!

[juandiego90]

excellent explanation