2023 · Q30
If x sin³θ + y cos³θ = sin θ cos θ and x sin θ − y cos θ = 0, for every θ ∈ (0, π/2), then what is x² + y² equal to?
Elementary MathematicsTrigonometry
- A0
- B1
- C2
- D3
Explanation
From x sin=y cos, put into first: x sin^3+x cos^2 sin=sin cos, so x sin=cos... solving gives x^2+y^2=1. Option (b).