2010 HSC Q (2 Viewers)

[krypticlemonjuice]

For this question. I don't understand how they used (ii) to solve. Is there a certain property they used?? How do we do this question

 

[HSCya1234567]

Ah so I was stuck on this question, basically the formatting is weird, they want aii, which is the tan(A-B) = pi/2 thing from before, and then you use that to simplify the tan2thetatana