Math - Trigonometry - The Cosine Rule

[childishandmature2]

Who else likes the lesson as well as the accent! XD Lol

[verdugito1]

sorry dont square root answer haha

[verdugito1]

or you could just do (b2+c2-a2)divide(2 times b times c)= cos-1 square root answer= and u get the answer :)

[TheAlbo10]

Thanks for this video! helped a lot!

[Agrashsallam]

is it possible to find all sides and angles with these informations using the cosine rule?

B = 30

b = 12

c = 16

Cause I can't.

[divdawgd]

@Agrashsallam I think you can use sine law for that

[Agrashsallam]

@divdawgd

I know I can, but I was being told to do so with cosine and I were unable to do so.

[divdawgd]

@Agrashsallam Hmm I don't know how to do it with cosine, sorry :(

[expertmathstutor]

@Agrashsallam - divdawg is right you can use the sine rule. Check out the video on using the sine rule on my page, it's actually much easier than the cosine rule. SinB/b=sinC/c=sineA/a

[f15htechtips]

i got a C in my unit 2 (English CGSE) i need a B so this is great help for my re-take thanks :)

[Flextaa]

@f15htechtips Use the cosine rule in your English GCSE and you instafail xD

[f15htechtips]

@Flextaa i was explaining what a GCSE was saying it was English because other countries would call it different things but i get where you are coming from lol XD

[Flextaa]

@f15htechtips oh i see

[reza9945]

keep going u are the best teacher !!!!!!

[awat888]

thanks 

[rachana481]

@Joshuagrandmaster if all other sides are given in cm , then it'll be in cm . if rest is in mm then it'll also be in mm .

[Joshuagrandmaster]

thanks



[Joshuagrandmaster]

isit always in cm or can it be mm, just refreshing the mind anfter couple years

[DavnerMelodian]

Very helpful. Who cares if it's slow? Just easier to follow along! Thanks!

[hanolan11]

THANK YOU SO MUCH! I watched this yesterday and luckily enough, it came up on my gcse today, soo THAAAANNKKSSS!!!! :D xx

[mu51im]

Great video :) Plus I think he looks a bit like Elvis lol

[creameggxx]

ty so much !

[Fish4Bullets]

7:08 why does he put in -1 after the cos?

[sam84763]

@Fish4Bullets to work out the angle. if he was working out a side it would be normal: cos. however he is working out an angle so it is always cos-1 :)

[Funnyfrank12345]

@Fish4Bullets Becasue to find the angle we have to use the inverse operation, so get this on a calculator you have to press shift before you press cos, tan or sin

[andrewschmidtislegit]

@Fish4Bullets cause the "-1" means you're looking for an angle, if you dont use it, you're looking for a side!

[lizzielovesbeautyx]

thank you SOOOO MUCH, this really HELPED me x

[rizekelias]

it turns out that my math teacher has no idea how to explain things. thanks so much, i now have a fighting chance of passing my final tomorrow.

[jcoleshadow]

@rizekelias lool my final tommorow same situation :)



[Roxa1810]

Thanks, that was really helpful !

[KarolynLe]

This is a really good video. Just a few things.

1) You teach REALLY slowly.

2) You do realise that you have plenty of board space right? You don't need to cram it all onto one side.

[ComputerMaster1st]

May I borrow this video for my software I'm making.

My Software is called CMath 2 and I'm the only developer.

Here is a link to our Head Quarters. cmath2(dot)unlimitedtree(dot)c­­om