The principal value of ‘θ’ for which 2Tan−1cosθ=Tan−12cosce θ
π4
π6
π3
π2
We have 2Tan-1cosθ=Tan-12cosecθ
⇒Tan-12cosθ1-cos2θ=Tan-12sinθ⇒Tan-12cosθ1-cos2θ=Tan-12sinθ⇒2cosθsin2θ=2sinθ⇒cotθ=1⇒θ=π4