sin(θ-30°) = 1/2 হলে, cosθ এর মান কত?

প্রশ্ন

\sin(\theta-30^\circ) = \dfrac{1}{2}

হলে, \cos\theta এর মান কত?

উত্তর

\dfrac{1}{2}

ব্যাখ্যা / সমাধান

\therefore \sin(\theta-30^\circ) = \dfrac{1}{2}

\Rightarrow \sin(\theta-30^\circ) = \sin 30^\circ [\because \sin 30^\circ = \dfrac{1}{2}]

\Rightarrow \theta-30^\circ = 30^\circ

\Rightarrow \theta = 30^\circ + 30^\circ = 60^\circ

\therefore \cos\theta = \cos 60^\circ = \dfrac{1}{2}

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