2025 · Q35
What is the value of x, where 0 ≤ x ≤ 30^(∘), satisfying tan3x tan 6x = 1 ?
Elementary MathematicsTrigonometry
- A0^(∘)
- B10^(∘)
- C12^(∘)
- D15^(∘)
Explanation
tan 3x · tan 6x = 1 gives tan 6x = cot 3x = tan(90° − 3x), so 6x = 90° − 3x, i.e. 9x = 90° and x = 10°, which lies in [0°, 30°], option (b).