Math - Trigonometry - The Cosine Rule

Expertmathstutor shows how and when to use the Cosine Rule in Trigonometry when trying to find the length of an unknown side or the size of an unknown angle on a non right angled triangle. To buy a set of 7 DVD's with all the lessons go to www.expertmathstutor.com

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[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.

[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

[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.

[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 :)

[divdawgd]

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

[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 I think you can use sine law for that

[TheAlbo10]

Thanks for this video! helped a lot!