OldTimer

Hi Melody...apolgies for confusing you.....thanks for your patience in re-clarifying...such a great help...you are really talented!!

Hi Melody...so I had another look at the question (thanks to your feedback) and tried to keep it simple. 

So could the question be saying that the derivative of main function  is a maximum and is equal to square root of same function (ie  +/- values apply)...and therefore this is given and no need to prove it??!!

In that case I get the following for x (Word is terrible for writing power/equations so I hope there are no typos) - which agrees with book. Regards & thanks again

Hi Melody....thanks for your prompt  reply.

This is the answer (no 10)  offered in the book which also differs from your solution......heck (2nd time I met this circumstance)!

re 'do more to show it is a Max value' : I extracted 2 nd derivative which is a negative...thus pointing to a maximum value.

Thanks for your feedback & knowledge!

Thanks again Melody!! All the best to the Team!

Brilliant Melody.....In all honesty I was getting the same answer (not in such fine style!!) as your solution!

This proves there is an error in the book!! 

Therefore thanks a million and I wish you all the best for the festive season and assure you I am a great fan of yours!!   

Thanks for that...what a great job Heureka!!

I tried to solve this problem using sine rule. Therefore I got values of a and b independent of height of beacon! A bit puzzling.. 

Regards and thanks -  have a great day! 

Thanks Melody.....I think I got it now...hope you and Tiggsy approve. Great thanks!!

Dear all thanks for your help.....solved part 1 as follows:

Hi Melody.....Apologies....you are right of course. I got distracted by the Windows graphics and loading process to site. Will amend for correctness sake.