已知三角形的三边，求三角形的面积

小程序示例：

float area(float a, float b, float c)
{
    float t, s;
    t = (a + b + c) / 2;
    s = (float)sqrt(t*(t - a)*(t - b)*(t - c));     //求得面积
    return s;                                   //返回面积的值
}

int main()
{
    float s1, s2, s3,s4;
    s1 = area(6.3, 4.0, 7.5);
    s2 = area(7.5, 8.0, 3.7);
    s3 = area(5.2, 8.0, 6.1);
    s4 = s1 + s2 + s3;
    printf("多边形面积为%.1f\n",s4);
    system("pause");
}

运行结果：

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2017.10.19
1：27