задача 5

            Console.Write(" Entering a basis A (sm): ");
            double osnovaA = double.Parse(Console.ReadLine());
            osnovaA = Math.Abs(osnovaA);
            Console.WriteLine();

            Console.Write(" Entering a basis B (sm): ");
            double osnovaB = double.Parse(Console.ReadLine());
            osnovaB = Math.Abs(osnovaB);
            Console.WriteLine();

            Console.Write("Entering a height H (sm): ");
            double heightH = double.Parse(Console.ReadLine());
            heightH = Math.Abs(heightH);
            Console.WriteLine();

            double areaTrapeze = (osnovaA + osnovaB)*heightH/2;
            Console.WriteLine("                   area : " + areaTrapeze + " sm^2");