Trigonometrical Equations
hard

समीकरण $1+\sin ^{4} x =\cos ^{2} 3 x , x \in\left[-\frac{5 \pi}{2}, \frac{5 \pi}{2}\right]$ के हलों की संख्या हैं

A

$3$

B

$4$

C

$5$

D

$7$

(JEE MAIN-2019)

Solution

$1\, + \,{\sin ^4}x\, = \,{\cos ^2}3x$

$\sin \,x\, = \,0$  and  $\cos \,3x\, = 1$

$0,\,\,2\pi ,\, – \,2\pi ,\, – \,\pi ,\pi $

Standard 11
Mathematics

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