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1.8.6 Compound and double angle formulae (A-level only)

1.8.6 Compound and double angle formulae (A-level only)

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Question 35

The vertical displacement of a specialized laboratory sensor, VVV, is modelled by the function V(θ)=8cos⁡θ+15sin⁡θV(\theta) = 8\cos \theta + 15\sin \thetaV(θ)=8cosθ+15sinθ, where θ\thetaθ is the phase angle in radians.

a.

Express V(θ)V(\theta)V(θ) in the form Rcos⁡(θ−α)R\cos(\theta - \alpha)Rcos(θ−α), where R>0R > 0R>0 and 0<α<π20 < \alpha < \frac{\pi}{2}0<α<2π​. Give the exact value of RRR and the value of α\alphaα, in radians, to 3 decimal places.

[3]
b.

A secondary performance metric for the sensor, H(t)H(t)H(t), is defined by H(t)=12−3V(4t)H(t) = 12 - 3V(4t)H(t)=12−3V(4t), for t≥0t \ge 0t≥0, where ttt is the time in seconds.

Using the answer to part (a), (i) determine the exact maximum value of H(t)H(t)H(t). (ii) find the smallest positive value of ttt for which this maximum value occurs, giving your answer to 2 decimal places.

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Markscheme

1.8.6 Compound and double angle formulae (A-level only) Questions

  1. A Level
  2. /Maths
  3. /1.8.6 Compound and double angle formulae (A-level only)

46 exam-style questions on AQA A Level Maths 1.8.6 Compound and double angle formulae (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

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