Edexcel C3 — Question 8

Exam BoardEdexcel
ModuleC3 (Core Mathematics 3)
TopicHarmonic Form

  1. In a particular circuit the current, \(I\) amperes, is given by
$$I = 4 \sin \theta - 3 \cos \theta , \quad \theta > 0$$ where \(\theta\) is an angle related to the voltage. Given that \(I = R \sin ( \theta - \alpha )\), where \(R > 0\) and \(0 \leqslant \alpha < 360 ^ { \circ }\),
  1. find the value of \(R\), and the value of \(\alpha\) to 1 decimal place.
  2. Hence solve the equation \(4 \sin \theta - 3 \cos \theta = 3\) to find the values of \(\theta\) between 0 and \(360 ^ { \circ }\).
  3. Write down the greatest value for \(I\).
  4. Find the value of \(\theta\) between 0 and \(360 ^ { \circ }\) at which the greatest value of \(I\) occurs.
    8. continued