Trapezoidal Rule Method in C

A rule for estimating the area of an irregular figure, by dividing it into parallel strips of equal width, each strip being a trapezium. It can also be adapted to obtaining an approximate value of a definite integral.

Program of Trapezoidal Rule in C

   #include<stdio.h>
   #include<conio.h>
   #include<math.h>
   float func(float x)
   {
    float a;
    a=2*pow(x,2)+3*x;
    return a;
   }
   void main()
   {
    int n,i;
    float a,b,h,sum,integral;
    printf("\n Enter the upper limit: ");
    scanf ("%f",&a);
    printf("\n Enter the lower limit: ");
    scanf ("%f",&b);
    printf("\n Enter the interval: ");
    scanf ("%d",&n);
    h=(a-b)/n;
    sum=func(a)+func(b);
    i=2;
    while(i<=n)
    {
        sum=sum+2*func(b+(i-1)*h);
        i++;
    }
    integral=h*sum/2;
    printf("\n Answer is: %f",integral);
    
    getch();
}     
  

Output