三角形已知两边ab一角θ求第三边c

#include <stdio.h>
#include <math.h>
void cos(int a,int b,double θ)
{double pi=3.1415926;
double j=(θ/180)pi;
double c,C;
C=bb+aa-2abcos(double j);
c=sqrt(C);
printf("c=%.6lf",c);}
int main()
{cos(3,4,90.0);
return 0;
}

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

double fun(double a,double b,double ab)
{
    return sqrt(a*a+b*b-2*a*b*cos(ab* 3.1415926/180));
}
int main()
{
    printf("%f", fun(3,4,90));
}