CDS 2025 · PYQ · Trigonometric Equations · easy
What is the value of x, where 0 ≤ x < 30°, satisfying tan 3x tan 6x = 1?
Answer
The correct answer is B: 10°. tan 3x · tan 6x = 1 means tan 6x = cot 3x = tan(90° − 3x). So 6x = 90° − 3x, giving 9x = 90°, hence x = 10°.
- A.0°
- B.10°✓ Correct
- C.12°
- D.15°
tan 3x · tan 6x = 1 means tan 6x = cot 3x = tan(90° − 3x). So 6x = 90° − 3x, giving 9x = 90°, hence x = 10°.
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