NDA 2025
- Exam
- NDA
- Year
- 2025
- Subject
- Mathematics
- Chapter
- Trigonometric Equations
NDA 2025 · Mathematics · Trigonometric Equations
If 0 ≤ x ≤ (π)/(2) , then what is the number of values of x...
If , then what is the number of values of satisfying the equation ?
Options
- A
- B
- C
- D
Correct answer
B.
Step-by-step solution
The given equation is .
Rewriting the equation in terms of :
For the equation to be defined, , which means . Thus, x \in \left[0, \dfrac{\pi}{2}\right).<br><br>Multiplying both sides by\cos x\sin x + 1 = 2\cos^2 x\cos^2 x = 1 - \sin^2 x\sin x + 1 = 2(1 - \sin^2 x)2\sin^2 x + \sin x - 1 = 0(2\sin x - 1)(\sin x + 1) = 0\sin x = .
Since , . Therefore, is rejected.
For , the only solution in the given interval is .
Thus, there is exactly value of satisfying the equation.
Answer:
Rewriting the equation in terms of :
For the equation to be defined, , which means . Thus, x \in \left[0, \dfrac{\pi}{2}\right).<br><br>Multiplying both sides by\cos x\sin x + 1 = 2\cos^2 x\cos^2 x = 1 - \sin^2 x\sin x + 1 = 2(1 - \sin^2 x)2\sin^2 x + \sin x - 1 = 0(2\sin x - 1)(\sin x + 1) = 0\sin x = .
Since , . Therefore, is rejected.
For , the only solution in the given interval is .
Thus, there is exactly value of satisfying the equation.
Answer: