f (x) = 2cosx - 2cotx
f (x) = 2senx - cosx
f '(x) = 3secxtanx + 2sec²x
f (x) = 3tanx - 2cosx
f '(x) = 4tanxsecx + 3sec²x
f (x) = 4secx + 3tanx
f '(x) = -2senx + 2csc²x
f (x) = 4cscx - 3cotx
f '(x) = 3sec²x + 2senx
f (x) = 3senx + 2tanx
f '(x) = 3cosx + 2sec²x
f (x) = 3secx + 2tanx
f '(x) = 2cosx + senx
f '(x) = -4cotxcscx + 3csc²x
