Given that A+B =120¢ª and cos A + cos B = 1/¡î2 show that cos(A+B)/2 =1/¡î2

Answer 1

I could not make out your typing when you posted it under the name of "ceasar" , and I still can't make out what your symbols mean.

I have a feeling that 1/¡î2 means 1/√2 and 120¢ª is supposed to mean 120°

Please confirm before I do the question.