Calculate Area of a scalene triangle using C

#include<stdio.h>
#include<math.h>
main()
{
int s1,s2,angle;
float area;
printf("\n Enter Side1 : ");
scanf("%d",&s1);
printf("\n Enter Side2 : ");
scanf("%d",&s2);
printf("\n Enter included angle : ");
scanf("%d",&angle);
area = (s1 * s2 * sin((3.14/180)*angle))/2;
printf("\n Area of Scalene Triangle : %f",area);
}