Question 1169558
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The largest angle is opposite to the longest side.


By knowing is, we now can apply the cosine law to find cos(A), where A is the opposite angle to the side a= 40 cm


    a^2 = b^ + c^2 - 2bc*cos(A),


which implies


    cos(A) = {{{(12^2 + 34^2 - 40^2)/(2*12*34)}}} = -0.36765 = 1.9472 radians = 111.63 degrees.    <U>ANSWER</U>
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Solved.