1. The problem statement, all variables and given/known data http://img243.imageshack.us/img243/4339/69855059.jpg [Broken] 2. Relevant equations i've heard that the solution requires the use of the exponential taylor series: http://img31.imageshack.us/img31/6163/37267605.jpg [Broken] 3. The attempt at a solution i know that the first step is to convert cos(1/z) into it's complex number form which is: cos(1/z) = 0.5 (e^(i/z) + e^(-i/z)) I've tried manipulating 1/z and z^5 into the exp.taylor series but it gets messy (might be doing it wrong). any ideas would be great!