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If Cos X = − 1 2 and 0 < X < 2\Pi, Then the Solutions Are - Mathematics

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प्रश्न

If \[\cos x = - \frac{1}{2}\] and 0 < x < 2\pi, then the solutions are

विकल्प

  • \[x = \frac{\pi}{3}, \frac{4\pi}{3}\]

     

  • \[x = \frac{2\pi}{3}, \frac{4\pi}{3}\]

     

  • \[x = \frac{2\pi}{3}, \frac{7\pi}{6}\]

     

  • \[\theta = \frac{2\pi}{3}, \frac{5\pi}{3}\]

     

MCQ
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उत्तर

\[x = \frac{2\pi}{3}, \frac{4\pi}{3}\]
Given equation:
\[\cos x = - \frac{1}{2}\]
\[ \Rightarrow \cos x = \cos \frac{2\pi}{3}\]
\[ \Rightarrow x = \frac{2\pi}{3}\]
Or,
\[\cos x = \cos \frac{4\pi}{3}\]
\[ \Rightarrow x = \frac{4\pi}{3}\]
So, both 
\[\frac{2\pi}{3} \text{ and }\frac{4\pi}{3}\] lie in
\[0 < x < 2\pi\].
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अध्याय 11: Trigonometric equations - Exercise 11.3 [पृष्ठ २८]

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आरडी शर्मा Mathematics [English] Class 11
अध्याय 11 Trigonometric equations
Exercise 11.3 | Q 20 | पृष्ठ २८

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