2023 · Q72
If 7sin⁴θ + 9cos⁴θ + 42sin²θ = 16, 0 < θ < π/2, then what is tan θ equal to?
Elementary MathematicsTrigonometry
- A1
- B2
- C3
- D1/3
Explanation
7sin^4+9cos^4+42sin^2=16 with sin^2+cos^2=1 leads to tan^2=1/3, i.e. tan=1/sqrt3, not listed as printed. Keyed option (d). Key disputed: verify against the official UPSC key.