1 #include <stdio.h>
2 #include <math.h>
3 #include <stdlib.h>
4
5 #define eps 1e-8
6 #define pi acos(-1)
7
8 typedef struct SEG
9 {
10 double l, r;
11 }SEG;
12
13 typedef struct TPoint
14 {
15 double x, y;
16 }TPoint;
17
18 typedef struct TLine
19 {
20 double a, b, c;
21 }TLine;
22
23 typedef struct Circle
24 {
25 TPoint c;
26 double r;
27 }Circle;
28
29 double distance(double x1, double y1, double x2, double y2)
30 {
31 return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
32 }
33
34 TPoint LineInter(TLine l1, TLine l2)
35 {
36 //求两直线得交点坐标
37 TPoint tmp;
38 double a1 = l1.a;
39 double b1 = l1.b;
40 double c1 = l1.c;
41 double a2 = l2.a;
42 double b2 = l2.b;
43 double c2 = l2.c;
44 //注意这里b1 = 0
45 if(fabs(b1) < eps){
46 tmp.x = -c1 / a1;
47 tmp.y = (-c2 - a2 * tmp.x) / b2;
48 }
49 else{
50 tmp.x = (c1 * b2 - b1 * c2) / (b1 * a2 - b2 * a1);
51 tmp.y = (-c1 - a1 * tmp.x) / b1;
52 }
53 return tmp;
54 }
55
56 TLine lineFromSegment(TPoint p1, TPoint p2)
57 {
58 //线段所在直线,返回直线方程的三个系统
59 TLine tmp;
60 tmp.a = p2.y - p1.y;
61 tmp.b = p1.x - p2.x;
62 tmp.c = p2.x * p1.y - p1.x * p2.y;
63 return tmp;
64 }
65
66 int cmp(const void *a, const void *b)
67 {
68 SEG *c = (SEG *)a;
69 SEG *d = (SEG *)b;
70 if(c->l < d->l) return -1;
71 else return 1;
72 }
73
74 int main()
75 {
76 int n, i, j;
77 TPoint b, inter;
78 double lbc, lcinter, a, bangle;
79 double start, end;
80 TLine l1;
81 Circle circle[505];
82 SEG seg[505];
83
84 while(scanf("%d", &n) && n){
85 scanf("%lf%lf", &b.x, &b.y);
86 for(i = 0;i < n;i++){
87 scanf("%lf%lf%lf", &circle[i].c.x, &circle[i].c.y, &circle[i].r);
88 if(fabs(b.x - circle[i].c.x) < eps) a = pi / 2;
89 else a = atan((circle[i].c.y - b.y) / (circle[i].c.x - b.x));
90 if(a < 0) a += pi;
91 lbc = distance(b.x, b.y, circle[i].c.x, circle[i].c.y);
92 bangle = asin(circle[i].r / lbc);
93 l1 = lineFromSegment(b, circle[i].c);
94 inter.x = -l1.c / l1.a;
95 inter.y = 0.0;
96 lcinter = distance(inter.x, inter.y, b.x, b.y);
97 seg[i].l = inter.x - lcinter * circle[i].r / lbc / sin(a - bangle);
98 seg[i].r = inter.x + lcinter * circle[i].r / lbc / sin(pi - a - bangle);
99 }
100 qsort(seg, n, sizeof(seg[0]), cmp);
101 start = seg[0].l;
102 end = seg[0].r;
103 for(i = 1;i < n;i++){
104 if(seg[i].l > end){
105 printf("%.2lf %.2lf\n", start, end);
106 start = seg[i].l;
107 end = seg[i].r;
108 }
109 else {
110 if(seg[i].r > end) end = seg[i].r;
111 }
112 }
113 printf("%.2lf %.2lf\n\n", start, end);
114 }
115 return 0;
116 }
