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Question

If \(x^2 - 2x\cos\theta + 1 = 0\), then what is the magnitude of \(x\)?

This question was previously asked in
NDA 2 2026 GAT Question Paper (13-Sep-2026)
The correct answer is

\(1\)

Solving \(x^2-2x\cos\theta+1=0\) by the quadratic formula gives \(x=\cos\theta \pm i\sin\theta\), since \(\cos^2\theta-1=-\sin^2\theta\). The magnitude is \(|x|=\sqrt{\cos^2\theta+\sin^2\theta}=1\).

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