程序代码：

#include <stdio.h>
#include <math.h>
double multi(double a,double b);
int main(void)
{
    double a,b,k,s,h;
    int n=100;
    printf("请输入区间：");
    scanf("%f,%f",&a,&b);
    h=fabs(a-b)/n;
    k=h*((sin(a)+sin(b))/2.0);
    //s=h*(sin(a)+sin(b))/2.0+multi(a,b);
    printf("%0.5f,%0.5f,%0.5f",multi(a,b),k,h);
    //printf("%f",s);
    return 0;
}
double multi(double a,double b)
{
    int i=1,n=100;
    //double a=0,b=1.5;
    float h,sum=0;
    h=fabs(a-b)/n;
    do
    {
        sum+=sin(a+i*h);
        i++;
    }
    while(i<=99);
    //printf("%0.5f",sum);
    return sum;
}