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.