9709 P33 - Jun 2021 - Q6
1900
(a) By sketching a suitable pair of graphs, show that the equation \(\cot \frac{1}{2}x = 1 + e^{-x}\) has exactly one root in the interval \(0 < x \leq \pi\).
(b) Verify by calculation that this root lies between 1 and 1.5.
(c) Use the iterative formula \(x_{n+1} = 2 \arctan \left( \frac{1}{1 + e^{-x_n}} \right)\) to determine the root correct to 2 decimal places. Give the result of each iteration to 4 decimal places.
