find angle A if side a=34 side b=28 and side c=15 need help bad please help me

Question

anonymous · Answer

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do you know the Law of Cosines?

anonymous · Answer

no

anonymous · Answer

there are actually 3 but they're all basically the same... since you want Angle A, i'll write it out for you in it's most common form:

a^2 = b^2 + c^2 -2abcosA

anonymous · Answer

using this formula, solve for cosA... what do you have?

anonymous · Answer

34 is cos a

anonymous · Answer

forget about the lengths given for now... solve for cosA in terms of a, b, c.

anonymous · Answer

ok so if I have a 34 b 28 and c 15 would i have to times them all by their number again

anonymous · Answer

this gives you cosA.  Do you know how to find A from here?

anonymous · Answer

ya so if I add bsquared and c swuared I would get 666

anonymous · Answer

b^2 + c^2 = 666 ?

anonymous · Answer

ok I have no idea how to do it can you just do it really quick so I can learn from you how to do it please that would help a lot

anonymous · Answer

hang on, there's a problem here...

anonymous · Answer

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ok, that should be it.