ρcosθ=3,
ρ=4cosθ;
两式相除:
cosθ=3/4cosθ
(cosθ)^2=3/4
cosθ=根3/2,
0小于等于θ小于二分之π,θ=π/6
ρ=4cosθ=4*cos30=2根3
交点坐标(2根3,π/6)