The relation between polar coordinates(r,theta)(r,θ) and rectangular coordinates (x,y)(x,y) are given by x=rcosthatax=rcostˆa and y=rsinthetay=rsinθ and hence r=sqrt(x^2+y^2)r=√x2+y2
Hence x^2+(y-2)^2-4=0x2+(y−2)2−4=0 can be written as
x^2+y^2-4y+4-4=0x2+y2−4y+4−4=0 or using relations between polar and Cartesian coordinates