Exam question: Functions of complex variables
June 2015 question 2
The function  is used to approximate  for  where .
Construct a spreadsheet that will calculate the error in the real part of this approximation for different values of a. State the formulae you have used in your spreadsheet.
Use your spreadsheet to find, correct to 1 decimal place, the minimum positive value 
of a such that the real part of  exceeds the real part of  by more than 0.001.