1. The problem statement, all variables and given/known data http://puu.sh/2mrWM [Broken] I'm practicing for my upcoming exam on discrete mathematics (we're not really too far in yet), and I cannot no matter how hard I try prove the equations. I expand tan(k-1) and then multiply by tan(k) and always end up at a dead end, it is driving me crazy. I did however manage to do the summation without any problems... So can someone please shed some light as to the approach I need to take to complete the first part of the question?