float RadIncircle(float A, float B, float C)
{
    // Inradius formula: r = K / s
    // where K is the area and s is the semi-perimeter
    float s = (A + B + C) / 2.0;
    float K = sqrt(s * (s - A) * (s - B) * (s - C));
    return K / s;
}