Recursive Calculation of the Approximate Value of Sinus in C

#include< stdio.h> 
#include< stdlib.h> 

unsigned long fact_recursive (unsigned short nombre)
{
 if (number == 0)
 return 1; 
 else
 return number * fact_recursive(number - 1); 
}

unsigned int puiss(long int x, int n)
{
 if(n == 0)
 return 1; 
 if(n == 1)
 return x;
 int x2 = power(x,n/2); 
 if(n%2 == 0)
 return x2 * x2; 
 return x2 * x2 * x;
}

float Approx_sin(float x, int n)
{
 float fraction = (float)puiss(x,2*n-1) / (float)fact_recursive(2*n-1); 
 //Display
 if(n%2==1)
 printf("n = %d --> %f\n",n,fraction); 
 else
 printf("n = %d --> -%f\n",n,fraction); 

 //Terminal condition if n=1 then Approx_sin=x;
 if(n==1)
 {
 return x;
 }
 else{
 //if n is odd the sign is positive
 if(n%2==1)
 return calcul_formule(x, n-1)+fraction; 
 //if n is odd, the sign is negative
 else
 return calcul_formule(x,n-1)-fraction; 
 }
}

int main(int argc, char *argv[])
{
 int n; 
 float x;
 printf("Enter the value of x: "); 
 scanf("%d",& x); 
 printf("Enter the value of n: "); 
 scanf("%d",& n); 
 //formula calculation
 printf("Approx_sin(%f, %d ) = %f\n",x,Approx_sin(x,n) ); 
 system("pause"); 
}