Eroare de compilare: user.c: In function ‘main’: user.c:16:19: error: ‘M_PI’ undeclared (first use in this function) x = a * cos(M_PI / 4) - b * sin(M_PI / 4); ^ user.c:16:19: note: each undeclared identifier is reported only once for each function it appears in user.c:10:9: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d", &t); ^ user.c:13:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d", &n); ^ user.c:15:13: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d%d", &a, &b); ^