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TS EAMCET · Maths · Trigonometric Equations

If \(\triangle A B C\), if \(\cos A \cos B+\sin A \sin B \sin C=1\) and \(C=\frac{\pi}{2}\), then \(A: B=\)

  1. A \(1: 4\)
  2. B \(1: 3\)
  3. C \(1: 2\)
  4. D \(1: 1\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(1: 1\)

Step-by-step Solution

Detailed explanation

Given, \[ \begin{aligned} & \cos A \cos B+\sin A \sin B \sin C=1 \text { and } C=\frac{\pi}{2} \\ & \Rightarrow \quad \sin C=\sin \frac{\pi}{2}=1 \end{aligned} \] So, \(\cos A \cos B+\sin A \sin B(\mathrm{l})=\mathrm{l}\)…