How write code to caculate trapezium area

Dear Lecturer

My name is Deab Sina .
This is my video assignment.

Here is coding:

#include <stdio.h>

int main(void)
{
    float a, b, h, trapezium;
    printf("Input the side of trapezium: \n");
    printf("side a:"); scanf("%f", &a);
    printf("side b:"); scanf("%f", &b);
    printf("side h:"); scanf("%f", &h);

    trapezium = h * (a+b)/2; // this is syntax to calculate area trapezium
    printf("The Trapezium area =%.2f\n", trapezium);
    return 0;

}

This is the link to my video:
http://youtu.be/EUXt8QxNq8Q


Thanks,