直线 y = x 倾斜角是 π/4, y = √3x 倾斜角是 π/3, 见图。故得 π/4 ≤ θ ≤ π/3.曲线 2xy = 1 化为极坐标是 2 rsinθ rcosθ = 1, r^2 sin2θ = 1, r = 1/√sin2θ.同理，曲线 4xy = 1 化为极坐标是 r = 1/√(2sin2θ).见图, 故得 1/√(2sin2θ) ≤ r ≤ 1/√sin2θ.
