Program to illustrate the acos( ) function

    #include <iostream.h>
    #include <math.h>                      // defines the acos( ) function
    #include <conio.h>
    void main ()
    {
        double result ;
        double i = 0.5 ;
        result = acos ( i ) ;
        cout<<"\n The arc cosine of "<< i << " is "<< result;
        getch () ;
    }