JEE Main 2025 — Trigonometric Equations Question with Solution
JEE Main 2025 (22 Jan Shift 2)
Question
The sum of all values of satisfying and is
Choose an option
Show full solutionCorrect option: C
Correct answer
C
Step-by-step explanation
$\begin{aligned}
& 2 \sin ^2 \theta=\cos 2 \theta \\
& 2 \sin ^2 \theta=1-2 \sin ^2 \theta \\
& 4 \sin ^2 \theta=1 \\
& \sin ^2 \theta=\frac{1}{4} \\
& \sin \theta= \pm \frac{1}{2} \\
& 2 \cos ^2 \theta=3 \sin \theta \\
& 2-2 \sin ^2 \theta+3 \sin \theta-2=0 \\
& (2 \sin \theta-1)(2 \sin \theta-2)=0 \\
& \sin \theta=\frac{1}{2}
\end{aligned}$
so common equation which satisfy both equations is
Sum
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