Number of solutions of the trigonometric equation $2 \tan 2 \theta-\cot 2 \theta+1=0$ lying in the interval…

Number of solutions of the trigonometric equation $2 \tan 2 \theta-\cot 2 \theta+1=0$ lying in the interval $[0, \pi]$ is
  1. 2
  2. 3
  3. 4
  4. 5

Solution

$\begin{aligned} & \text { } 2 \tan 2 \theta-\cot 2 \theta+1=0 \\ & \text { Let } \tan 2 \theta=x \Rightarrow 2 x-\frac{1}{x}+1=0 \\ & \Rightarrow 2 x^2+x-1=0 \Rightarrow x=-1, \frac{1}{2} \\ & \Rightarrow \tan 2 \theta=-1, \frac{1}{2}\end{aligned}$
$\therefore$ Required number of solutions are 4.

Asked in: AP EAMCET 2024 (21 May Shift 2)

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