1. ## Anomaly in problem

(see attached thumbnail)
Where did I go wrong?

3. ## Re: Anomaly in problem

thank you but please tell me what was wrong in what i did.

4. ## Re: Anomaly in problem

there is nothing wrong but you did not start the proof at all. you have just used the condition A + B + C = pi to simplify the expression. the proof starts thereafter. That is why I started from where you left ok.

5. ## Re: Anomaly in problem

the given condition was A+B+B=pi
I don't understand how i got A+B+C=pi/2