Express in harmonic form

A question is this type if and only if it asks to express a linear combination of sin and cos (e.g., a·sin(θ) + b·cos(θ)) in the form R·sin(θ ± α) or R·cos(θ ± α), without requiring further solving.

4 questions · Moderate -0.9

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OCR MEI C4 2016 June Q1
6 marks Moderate -0.3
1 Express \(\cos \theta - 3 \sin \theta\) in the form \(R \cos ( \theta + \alpha )\), where \(R > 0\) and \(0 < \alpha < \frac { \pi } { 2 }\).
Hence show that the equation \(\cos \theta - 3 \sin \theta = 4\) has no solution.
OCR MEI Paper 2 2022 June Q1
4 marks Moderate -0.5
1 Express \(\cos \theta + \sqrt { 3 } \sin \theta\) in the form \(R \cos ( \theta - \alpha )\), where \(R\) and \(\alpha\) are exact values to be determined.
AQA Paper 3 2020 June Q2
1 marks Easy -1.2
2 Given that $$6 \cos \theta + 8 \sin \theta \equiv R \cos ( \theta + \alpha )$$ find the value of \(R\). Circle your answer. 681014
AQA Paper 3 2020 June Q8
12 marks Easy -1.8
8
17 2 Given that $$6 \cos \theta + 8 \sin \theta \equiv R \cos ( \theta + \alpha )$$ find the value of \(R\). Circle your answer. 681014 3 Determine which one of these graphs does not represent \(y\) as a function of \(x\). Tick \(( \checkmark )\) one box. \includegraphics[max width=\textwidth, alt={}, center]{076ea8e9-9295-46d2-b5f9-b27fa969129e-03_2246_974_443_495} 4
  1. Use the factor theorem to prove that \(x - 6\) is a factor of \(\mathrm { p } ( x )\). \(4 \quad \mathrm { p } ( x ) = 4 x ^ { 3 } - 15 x ^ { 2 } - 48 x - 36\) 4
    1. Prove that the graph of \(y = \mathrm { p } ( x )\) intersects the \(x\)-axis at exactly one point.
      4
  2. (ii) State the coordinates of this point of intersection.