解析：ρ²=4/(1+3sinθ)4/ρ²=1+3sinθ4/ρ²-1=3sinθ(4/ρ²-1)²=9sin²θ(4/ρ²-1)²ρ⁴=9sin²θρ²●ρ²(4-ρ²)²=9(ρsinθ)²●ρ²(4-x²-y²)²=9y²(x²+y²)
