Processing Math: Done

From Förberedande kurs i matematik 1

If we write the equation as

(x−0)2+(y−0)2=9

we can interpret the left-hand side as the square of the distance between the points (x,y) and (0,0). The whole equation says that the distance from a point (x,y) to the origin should be constant and equal to 9=3 , which describes a circle with its centre at the origin and radius 3.