The number of solution of $\tan x+\sec x=2 \cos x$ in $[0,2 \pi)$ is

The number of solution of $\tan x+\sec x=2 \cos x$ in $[0,2 \pi)$ is
  1. 2
  2. 3
  3. 0
  4. 1

Solution

The given equation is $\tan x+\sec x=2 \cos x \Rightarrow \sin x+1=2 \cos ^2 x$ $ \begin{aligned} & \Rightarrow \sin x+1=2\left(1-\sin ^2 x\right) \Rightarrow 2 \sin ^2 x+\sin x-1=0 \\ & \Rightarrow(2 \sin x-1)(\sin x+1)=0 \Rightarrow \sin x=\frac{1}{2},-1 \Rightarrow x=30^{\circ}, 150^{\circ}, 270^{\circ} \end{aligned} $

Asked in: JEE Main 2002

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