If cos 2θ = sin 4θ, here 2θ, 4θ are acute angles, then the value of ‘θ’ = A) 60° B) 30° C) 45° D) 15°
If cos 2θ = sin 4θ, here 2θ, 4θ are acute angles, then the value of ‘θ’ =
A) 60°
B) 30°
C) 45°
D) 15°
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Correct option is: D) 15°
Given that cos (2\(\theta\)) = sin (4\(\theta\)), where 2\(\theta\) & 4\(\theta\)are acute angles.
\(\therefore\) sin (\(90^\circ\) - 2\(\theta\)) = sin 4\(\theta\) (\(\because\) \(90^\circ\) -2\(\theta\) & 4\(\theta\) both are acute angles)
= 4\(\theta\) + 2\(\theta\) = \(90^\circ\)
= 6\(\theta\) = \(90^\circ\)
= \(\theta\) = \(\frac {90^\circ}6\) = \(15^\circ\)
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