SOLUTION: Find the largest angle of the Triangle whose sides are 7cm,5cm,3cm

Question 1028875: Find the largest angle of the Triangle whose sides are 7cm,5cm,3cm
Answer by ikleyn(52894) (Show Source): You can put this solution on YOUR website!
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Find the largest angle of the Triangle whose sides are 7cm,5cm,3cm
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The largest angle    is opposite to the longest side, which is 7 cm.

So from the Cosines Law theorem  (see, for example, the lesson  Proof of the Law of Cosines revisited  in this site),  you have 


 = ,   or

 = ,   or

 = ,   or

 = ,   or

 =  = .

Hence,   = 120 degrees.

Answer.   = 120 degrees.

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