Doubt from Solution of triangle


i did this but don'tknow what values to put for A,C ans is C


as you did write 2\cot(\frac{B}{2}) =\cot(\frac{A}{2}) + \cot(\frac{C}{2}) and add \cot(\frac{B}{2}) on both sides and use the identity \\ \cot(\frac{B}{2}) \cot(\frac{A}{2}) \cot(\frac{C}{2}) = \cot(\frac{B}{2}) +\cot(\frac{A}{2}) +\cot(\frac{C}{2})
to get \cot(\frac{A}{2}) \cot(\frac{C}{2}) = 3
which gives you the answer :slight_smile:

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use \displaystyle r = \frac{\Delta}{s}
s = 40,\Delta = 18by Heron's formula

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