área de un triangulo

lic double areaTriangle(double a, double b, double c)
{
    return (a * b * Math.Sqrt(Math.Pow(c, 2) - Math.Pow(a, 2) - Math.Pow(b, 2))) / 2;
}

public double areaSquare(double a)
{
    return a * a;
}

public double area