Trials urgent help needed (1 Viewer)

[iamorbid]

http://www.boardofstudies.nsw.edu.au/hsc_exams/hsc2011exams/pdf_doc/2011-hsc-exam-general-maths.pdf

For question 27 a) and b)

a) Doesn't have all the info I need, wtf is this?

b) I thought if they were on the SAME side we subtract and DIFFERENT we add, the answer is apparently 91 degrees.

 

[crimsonchin]

b) 109E + 160W= 269 ( add because theyre different) but because it's over 180 it's shorter to go the other way around so it's 360-269=91 or 180-109= 71 and 180-160=20 so 71+20 = 91
then 91/360*2*(pi)*6400

 

[iamorbid]

b) 109E + 160W= 269 ( add because theyre different) but because it's over 180 it's shorter to go the other way around so it's 360-269=91 or 180-109= 71 and 180-160=20 so 71+20 = 91
then 91/360*2*(pi)*6400

So do I use this method whenever I get a 180+ answer?
just subtract from a 360 and work through the equation?