#3TrapezoidArea

static void Main()
        {
            Console.WriteLine("Enter trapezoid's base A: ");
            float baseA = float.Parse(Console.ReadLine());
            Console.WriteLine("Enter trapezoid's base B: ");
            float baseB = float.Parse(Console.ReadLine());
            Console.WriteLine("Enter trapezoid's height H: ");
            float height = float.Parse(Console.ReadLine());
            float area = ((baseA + baseB) * height) / 2;
            Console.WriteLine("Trapezoid's area is: {0}", area);
        }