ρ=4sinθρ^2=4ρsinθx^2+y^2=4yx^2+(y-2)^2=4圆心为(0,2).点A(4,π/6)(2根号3,2).点A(4,π/6)到圆心C的距离=根号(12)=2根号3.
转换成直角坐标系：根号x^2+y^2=4y/根号x^2+y^2,即x^2+(y-2)^2=4,A=(2根号3,2),故距离为2根号3
