AQA Paper 1 2022 June — Question 10 2 marks

Exam BoardAQA
ModulePaper 1 (Paper 1)
Year2022
SessionJune
Marks2
TopicRadians, Arc Length and Sector Area

10 The diagram shows a sector of a circle \(O A B\).
\includegraphics[max width=\textwidth, alt={}, center]{22ff390e-1360-43bd-8c7f-3d2b58627e91-16_758_796_360_623} The point \(C\) lies on \(O B\) such that \(A C\) is perpendicular to \(O B\).
Angle \(A O B\) is \(\theta\) radians.
10
  1. Given the area of the triangle \(O A C\) is half the area of the sector \(O A B\), show that $$\theta = \sin 2 \theta$$ 10
  2. Use a suitable change of sign to show that a solution to the equation $$\theta = \sin 2 \theta$$ lies in the interval given by \(\theta \in \left[ \frac { \pi } { 5 } , \frac { 2 \pi } { 5 } \right]\)
    10
  3. The Newton-Raphson method is used to find an approximate solution to the equation
  4. \(\theta = \sin 2 \theta\)
    10
    1. Using \(\theta _ { 1 } = \frac { \pi } { 5 }\) as a first approximation for \(\theta\) apply the Newton-Raphson method twice
  5. to find the value of \(\theta _ { 3 }\) Give your answer to three decimal places.
    10
  • (ii) Explain how a more accurate approximation for \(\theta\) can be found using the Newton-Raphson method.
    10
  • (iii) Explain why using \(\theta _ { 1 } = \frac { \pi } { 6 }\) as a first approximation in the Newton-Raphson method
    [0pt] [2 marks] does not lead to a solution for \(\theta\).