Medium INTEGER +4 / -1 PYQ · JEE Mains 2021

If $\sqrt 3 ({\cos ^2}x) = (\sqrt 3 - 1)\cos x + 1$, the number of solutions of the given equation when $x \in \left[ {0,{\pi \over 2}} \right]$ is __________.

Answer (integer) 1

Solution

$\sqrt 3 ({\cos ^2}x) = (\sqrt 3 - 1)\cos x + 1$ <br><br>$\Rightarrow$ $\sqrt 3 {\cos ^2}x - \sqrt 3 \cos x + \cos x - 1 = 0$<br><br>$\Rightarrow \sqrt 3 \cos x(\cos x - 1) + (\cos x - 1) = 0$<br><br> $\Rightarrow (\cos x - 1)(\sqrt 3 \cos x + 1) = 0$<br><br>$\cos x = 1$<br><br>$\Rightarrow x = 0$ $[as x \in \left[ {0,{\pi \over 2}} \right]$]<br><br>and $\cos x = - {1 \over {\sqrt 3 }}$ (not possible in $x \in \left[ {0,{\pi \over 2}} \right]$] <br><br>$\therefore$ Number of solution = 1

About this question

Subject: Mathematics · Chapter: Trigonometric Functions · Topic: Trigonometric Equations

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