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Wednesday, 01 July 2026
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Express \(r = (12, 210°)\) in the form \(a i + b j\).

Express \(r = (12, 210°)\) in the form \(a i + b j\).
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  • A \(6(-i + \sqrt{3} j)\)
  • B \(6(-\sqrt{3} i - j)\)
  • C \(6(i - \sqrt{3} j)\)
  • D \(6(i + \sqrt{3} j)\)
Correct Answer: Option B
Explanation:
\(F = F \cos \theta i + F \sin \theta j\)
\(r = (12, 210°) = 12 \cos 210 i + 12 \sin 210 j\)
= \(- 6\sqrt{3} i - 6j\)
= \(6(-\sqrt{3} i - j)\)

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