solve lightOj 1331 - Agent J in c++

#include<iostream>
#include<math.h>
#include<iomanip>
using namespace std;
#define PI acos(-1)
int main()
{
    int t, i;
    double res, tri_area, r1, r2, r3, a, b, c, angle_a, angle_b, angle_c, area_r1, area_r2, area_r3, s;
    cin >> t;
    for(i = 1; i <= t; i++)
    {
        cin >> r1 >> r2 >> r3;
        a = r1 + r2;
        b = r1 + r3;
        c = r2 + r3;
        angle_a = acos((b*b + c*c - a*a) / (2 * b * c)) * 180.0/PI;
        angle_b = acos((a*a + c*c - b*b) / (2 * a * c)) * 180.0/PI;
        angle_c = acos((b*b + a*a - c*c) / (2 * b * a)) * 180.0/PI;
        area_r1 = 0.5 * (r1 * r1) * (angle_c * (PI/180.0));
        area_r2 = 0.5 * (r2 * r2) * (angle_b * (PI/180.0));
        area_r3 = 0.5 * (r3 * r3) * (angle_a * (PI/180.0));
        s = (a + b + c) / 2.0;
        tri_area = sqrt(s * (s - a) * (s - b) * (s - c));
        res = tri_area - (area_r1 + area_r2 + area_r3);
        cout << "Case " << i << ": " << fixed << setprecision(10) << res << endl;
    }
    return 0;
}

ahmed shuvo 969