Trigonometrical Equations
medium

समीकरण $3{\sin ^2}x + 10\cos x - 6 = 0$ का व्यापक हल होगा

A

$x = n\pi \pm {\cos ^{ - 1}}(1/3)$

B

$x = 2n\pi \pm {\cos ^{ - 1}}(1/3)$

C

$x = n\pi \pm {\cos ^{ - 1}}(1/6)$

D

$x = 2n\pi \pm {\cos ^{ - 1}}(1/6)$

Solution

$3{\sin ^2}x + 10\cos x – 6 = 0$

$3(1 – {\cos ^2}x) + 10\cos x – 6 = 0$

हल करने पर, $(\cos x – 3)\,(3\cos x – 1) = 0$

या तो $\cos x = 3$, (जोकि संभव नहीं है) या

$\cos x =\frac{1}{3}$ $ \Rightarrow \,\,x = 2n\pi  \pm {\cos ^{ – 1}}(1/3)$.

Standard 11
Mathematics

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