Question:
If cot θ + tan θ = 2 cosec θ, then find the general value of θ.
Solution:
According to the question,
$\Rightarrow \frac{\cos \theta}{\sin \theta}+\frac{\sin \theta}{\cos \theta}=2 \operatorname{cosec} \theta$
Since,
$\sin ^{2} \theta+\cos ^{2} \theta=1$
$\Rightarrow \frac{\cos ^{2} \theta+\sin ^{2} \theta}{\sin \theta \cos \theta}=2 \operatorname{cosec} \theta$
⇒ 1 = 2 cosec θ sin θ cos θ
We know that,
sin θ cosec θ = 1
⇒ 1 = 2 cos θ
⇒ cos θ = 1/2 = cos(π/3)
Hence,
The solution of cos x = cos α can be given by,
x = 2mπ ± α ∀ m ∈ Z
⇒ θ = 2nπ ± π/3, n ∈ Z