/* 
 * Example of using C library functions 
 *
 * Compute the length of the third side using the formula
 *   a^2 = b^2 + c^2 - 2*b*c*cos(alpha)
 * where b and c are the lengths of two sides of a triangle, and
 * alpha is the angle between them in degree 
 * Hanly and Koffman, Example 3.3, page 110
 * 
 */ 

#include <stdio.h> 
#include <math.h> 
#define PI 3.14159 

int
main(void)
{
    double a, b, c, alpha; 

    printf("Input the lengths of two sides b and c > ",b,c);  
    scanf("%lf%lf",&b,&c);    
    printf("and the angle between them in degree >", &alpha); 
    scanf("%lf",&alpha);    

    /* compute the length of third side */ 
    a = sqrt(pow(b,2) + pow(c,2) - 2 * b * c * cos(alpha * PI / 180.0)); 
 
    printf("Length of the third side a = %.2f\n",a); 

    return 0;  
}