1)#include < iostream > 2)# include < math.h > 3)using namespace std; 4)double max(double x,doubley); 5)void main() 6){ 7)double a,b,c; 8)cout << " input two numbers:/n"; 9)cin>>a>>b; 10)c=max(a,b); 11)cout<< " the squart of max imum="<< sqrt(c); 12)} 13)double max(doublex,doubley) 14){ 15)if(x>y) 16)returnx; 17)else 18)returny; 19)} 11行中sqrt( c )在哪个头文件中定义:()