# Best wishes and Good luck in your first year.

• posted
Crib notes or Cheat sheets.
"Trigonometry"
e^(iwt) = cos(wt) + isin(wt)
i^2 = -1 and +i = squareroot(-1).
-> 2(i)sin(wt) = [e^(iwt) - e^(-iwt)].
-> 2cos(wt) = [e^(iwt) + e^(-iwt)].
-> 2sinh(wt) = [e^(-i(iwt)) - e^(i(iwt))] = [e^(wt) - e^(-wt)]= 2sin(-iwt)) = -2sin(iwt).
-> 2cosh(wt) = (e^(-i(iwt)) + e^(i(iwt))) = (e^(wt) + e^(-wt)) = 2cos(iwt).
Further identities and such can be easier if
aside (that I found interesting): e^(irwt) = cos(rwt) + isin(rwt) = (cos(wt) + isin(wt))^r.
"polar notation".
"(angle)" being that "
• posted
e^(irwt) = cos(rwt) + isin(rwt) = (cos(wt) + isin(wt))^r. > > > > > > "polar notation". > > > > "(angle)" being that "
• posted
to be honest my refresher but if it help i'm happy.
"Trigonometry" e^(iwt) = cos(wt) + isin(wt) i^2 = -1 and i = squareroot(-1). 2(i)sin(wt) = [e^(iwt) - e^(-iwt)]. 2cos(wt) = [e^(iwt) + e^(-iwt)].
2sinh(wt) = [e^(-i(iwt)) - e^(i(iwt))] = [e^(wt) - e^(-wt)]= 2sin(-iwt)) = -2sin(iwt). 2cosh(wt) = (e^(-i(iwt)) + e^(i(iwt))) = (e^(wt) + e^(-wt)) = 2cos(iwt).
Further identities and such can be easier if