2024 SJI P2 Q9

2024 SJI P2 Q9

IB Year 5 | Grade 11
13 marks

The complex numbers \(z\) and \(w\) are represented by Z and W respectively on an Argand diagram. It is given that \(z=-\sqrt3-\mathrm i\) and \(w=1-\mathrm i\).

  1. Plot point Z and point W on an Argand diagram.[2]
  2. Find the exact value of the modulus and argument of \(z\) and of \(w\).[3]
  3. Hence find the area of triangle OZW, where O is the origin.[2]
  4. Given that \(v=\dfrac w{z^*}\), find \(\arg v\) where \(-\pi<\arg v\leq\pi\).[3]
  5. Find the smallest positive integer \(n\) such that \(v^n\) is purely imaginary.[3]

Solution:

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Answer:(a) \(Z(-\sqrt3,-1),W(1,-1)\) (b) \(|z|=2,\arg z=-5\pi/6;|w|=\sqrt2,\arg w=-\pi/4\) (c) \(1.37\text{ units}^2\) (d) \(11\pi/12\) (e) \(6\)

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