oop2

void draw_circle(int x0,int y0){
    double r,x,y;
    r=1;
    x=x0;
    y=y0;
    float step= pi/6;
    for (float f=0; f<=2*pi; f+=step){
        draw_line(x,y,cos(f)*r,sin(f)*r);
        x=cos(f)*r;
        y=sin(f)*r;
    }

}