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\(2sin\theta cos\theta=cos\theta\)
বা, \(2sin\theta cos\theta-cos\theta=0\)
বা, \(cos\theta(2sin\theta -1)=0\)
\(\therefore \) হয় \(cos\theta=0\)
বা, \(cos\theta=cos 90^o\)
বা, \(\theta=90^o\)

নয়, \(2sin\theta -1=0\)
বা, \(2sin\theta=1\)
বা, \(sin\theta=\cfrac{1}{2}=sin 30^o\)
বা, \(\theta=30^o\)

\(\therefore \theta = 90^o\) অথবা \(30^o\)