If A+B+C=pi &cosA=cosB*cosC,then prove

The given result for (i) is incorrect.  It is easy to tell it is wrong by letting A=B=C=pi/3, for example (tan(pi/3) = sqrt(3)).

Derivation of correct result for (i) and proof of (ii) below:

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My reply above that part (i) is incorrect is itself incorrect!! (I forgot about the cos A = cos B*cos C bit!)