```
#include <iostream>
#include <cmath>
using namespace std;
int main()
{//begin main
double hypot(double,double);
double base;
double height;
cout<<"Program to compute the Hypotenuse of a given right triangle. \n"<<endl;
cout<<"Enter the base: \n"<< endl;
cin>>base;
cout<<"Enter the height: \n"<<endl;
cin>>height;
cout <<"The hypothenus of given triangle is " << hypot(base,height) <<endl;
system("pause");
return 0;
}//end main
double hypot(double base, double height)
{//begin function
double newb=pow(base,2.0);
double newh=pow(height,2.0);
double newa=newb+newh;
double hyp= pow(newa,.5);
return hyp;
}//end function
```

[Linker error] undefined reference to `hypot(double, double)'

Why is this happening?