If \(\cos 6\theta=\sin 3\theta\), then the value of \(\theta\) is:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 10°
For acute angles, \(\cos x=\sin(90^\circ-x)\). So when the cosine of one angle equals the sine of another, the two angles are complementary: they add up to 90°.
\(\cos 6\theta=\sin 3\theta\) gives \(6\theta+3\theta=90^\circ\)
\(9\theta=90^\circ\), so \(\theta=10^\circ\)