#include <stdio.h> #include <stdlib.h> #include<math.h> int main() { int s; double x1, x2, y1, y2, m, a, b, c, PI = 3.1415926; scanf("%d", &s); while (s--) { scanf("%lf%lf%lf%lf", &x1, &y1, &x2, &y2); a = (x1*x1) + (y1*y1); a = sqrt(a); b = (x2*x2) + (y2*y2); b = sqrt(b); c = (x1 - x2)*(x1 - x2) + (y1 - y2)*(y1 - y2); c = sqrt(c); m = (a*a + b * b - c * c) / (2 * a*b); m = acos(m); //转换为弧度 m = m * 180 / PI; //弧度公式为1rad=180°/π printf("%.2lf\n", m); } return 0; }
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