# ```tanAtanB =square root of(a-b)/(a+b),prove that (a-bcos2A)(a--bcos2B)=a^2-b^2```

Grade:12

## 1 Answers

Aman Bansal
592 Points
11 years ago

Dear Aditya,

Another commonly-used set of formulae allows us to turn a product of sines and cosines into a sum or difference of sines and cosines. Here they are:

sin(A)+sin(B)=2sin{(A+B)/2}cos{(A-B)/2}

sin(A)-sin(B)=2cos{(A+B)/2}sin{(A-B)/2}

cos(A)+cos(B)=2cos{(A+B)/2}cos{(A-B)/2}

cos(A)-cos(B)=-2sin{(A+B)/2}sin{(A-B)/2}.

Cracking IIT just got more exciting,It s not just all about getting assistance from IITians, alongside Target Achievement and Rewards play an important role. ASKIITIANS has it all for you, wherein you get assistance only from IITians for your preparation and win by answering queries in the discussion forums. Reward points 5 + 15 for all those who upload their pic and download the ASKIITIANS Toolbar, just a simple  to download the toolbar….

So start the brain storming…. become a leader with Elite Expert League ASKIITIANS

Thanks

Aman Bansal

Askiitian Expert

## ASK QUESTION

Get your questions answered by the expert for free