Question : If $\sec 3 {x}=\operatorname{cosec}\left(3 {x}-45^{\circ}\right)$, where $3x$ is an acute angle, then ${x}$ is equal to:
Option 1: $45^{\circ}$
Option 2: $22.5^{\circ}$
Option 3: $35^{\circ}$
Option 4: $27.5^{\circ}$
Correct Answer: $22.5^{\circ}$
Solution :
Given that $\sec 3x = \operatorname{cosec}(3x - 45^\circ)$,
$⇒\frac{1}{\cos 3x} = \frac{1}{\sin(3x - 45^\circ)}$
$⇒\cos 3x = \sin(3x - 45^\circ)$
We know that $\sin(90^\circ - \theta) = \cos \theta$.
$⇒ 90^\circ -3x = 3x - 45^\circ$
Solving for $x$, we get:
$⇒6x = 135^\circ$
$⇒x = 22.5^\circ$
Hence, the correct answer is $22.5^\circ$.
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