C语言想用引入函数来求三角形的第三边 但是结果一直是0.00000不知道哪里出问题了

#include<stdio.h>
#include<math.h>

double hypotenuse(double a,double b);

int main()
{

    double a,b,f;
    printf("Please enter the length of both sides:");
    /*scanf("%f","%f",&a,&b);*/

    scanf("%f",&a);
    scanf("%f",&b);
    f= hypotenuse(a,b);
    printf("The hypotenuse of a triangle is %f",f);
    return 0;

}

double hypotenuse(double c,double d)
{
    double e;
    e=sqrt(c*c+d*d);

    return e;
}

结果一直是0.0000