JEE Mains · Maths · STD 11 - Trigonometrical equations
The number of solutions of the equation \(1 + {\sin ^4}\,x = {\cos ^2}\,3x,x\,\in \,\left[ { - \frac{{5\pi }}{2},\frac{{5\pi }}{2}} \right]\) is
- A \(3\)
- B \(4\)
- C \(5\)
- D \(7\)
Answer & Solution
Correct Answer
(C) \(5\)
Step-by-step Solution
Detailed explanation
\(1\, + \,{\sin ^4}x\, = \,{\cos ^2}3x\) \(\sin \,x\, = \,0\) and \(\cos \,3x\, = 1\) \(0,\,\,2\pi ,\, - \,2\pi ,\, - \,\pi ,\pi \)
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