WBJEE · Maths · Trigonometric Equations
Which of the following statements is /are correct for \(0 < \theta < \frac{\pi}{2} ?\)
- A \((\cos \theta)^{1 / 2} \leq \cos \frac{\theta}{2}\)
- B \((\cos \theta)^{3 / 4} \geq \cos \frac{3 \theta}{4}\)
- C \(\cos \frac{5 \theta}{6} \geq(\cos \theta)^{5 / 6}\)
- D \(\cos \frac{70}{8} \leq(\cos \theta)^{7 / 8}\)
Answer & Solution
Correct Answer
(C) \(\cos \frac{5 \theta}{6} \geq(\cos \theta)^{5 / 6}\)
Step-by-step Solution
Detailed explanation
\(0 \frac{\theta}{2},\) then \(\cos \theta \leq \cos \frac{\theta}{2}\) \(\therefore \quad \sqrt{\cos \theta} \leq \cos \frac{\theta}{2} \quad\) correct (b) When \(0>\frac{30}{4},\) then \(\cos \theta \leq \cos \frac{30}{4}\)…
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