Compilare: user.c: In function ‘main’: user.c:24:5: warning: implicit declaration of function ‘sqrt’ [-Wimplicit-function-declaration] double d = sqrt((x2-x1)*(x2-x1) + (y2-y1)*(y2-y1)); ^ user.c:24:16: warning: incompatible implicit declaration of built-in function ‘sqrt’ [enabled by default] double d = sqrt((x2-x1)*(x2-x1) + (y2-y1)*(y2-y1)); ^ user.c:30:5: warning: implicit declaration of function ‘acos’ [-Wimplicit-function-declaration] double part1 = r*r*acos((d*d + r*r - R*R)/(2*d*r)); ^ user.c:30:24: warning: incompatible implicit declaration of built-in function ‘acos’ [enabled by default] double part1 = r*r*acos((d*d + r*r - R*R)/(2*d*r)); ^ user.c:10:7: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(file1, "%lf", &T); ^ user.c:14:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(file1, "%lf", &x1); ^ user.c:15:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(file1, "%lf", &y1); ^ user.c:16:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(file1, "%lf", &radius1); ^ user.c:17:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(file1, "%lf", &x2); ^ user.c:18:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(file1, "%lf", &y2); ^ user.c:19:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(file1, "%lf", &radius2); ^ user.c:20:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(file1, "%lf", &A); ^