NTA Abhyas 2020
- Exam
- NTA Abhyas
- Year
- 2020
- Subject
- Mathematics
- Chapter
- Trigonometric Equations
NTA Abhyas 2020 · Mathematics · Trigonometric Equations
If A = \ θ: 2 ^ 2 θ + sin θ ≤ 2\ and B = \ θ: (π)/(2) ≤ θ ≤...
If and , then is equal to
Options
- A
- B
- C\left\{\theta: \dfrac{\pi}{2} \le \theta \le \dfrac{5\pi}{6}\right\}~or& \left\{\theta: \pi \le \theta \le \dfrac{3\pi}{2}\right\}
- D
Correct answer
C. \left\{\theta: \dfrac{\pi}{2} \le \theta \le \dfrac{5\pi}{6}\right\}~or& \left\{\theta: \pi \le \theta \le \dfrac{3\pi}{2}\right\}
Step-by-step solution
2 - 2\sin^{2} \theta + sin \theta \le 22\sin^{2} \theta - sin \theta \ge 0sin \theta\left(2sin \theta - 1\right) \ge 0sin \theta \ge 0, sin \theta \ge \dfrac{1}{2}⇒ sin \theta \ge \dfrac{1}{2} ⇒ \theta \in \left[\dfrac{\pi}{2}, \dfrac{5\pi}{6}\right]sin \theta \le 0, sin \theta \le \dfrac{1}{2}⇒ sin \theta \le 0⇒ \theta \in \left[\pi, \dfrac{3\pi}{2}\right]⇒ A \cap B = \left\{\theta: \dfrac{\pi}{2} \le \theta \le \dfrac{5\pi}{6}\right\}