title: no suitable method found to override c#
body: <p>I have tried a few things to fix the error and I just can't seem to figure this one out, I would greatly appreciate any help. The error is in both the Triangle and Square classes, the errors in Triangle are "does not implement inherited abstract member from GeometricFigure" and "no suitable method found to override" and Square has just the "no suitable method found to override" error.</p>
  
  <pre><code>namespace ShapesDemo
  {
      class Program
      {
          static void Main(string[] args)
          {
              Rectangle rec = new Rectangle(8,10);
              Square squ = new Square(11, 12);
              Triangle tri = new Triangle(10, 20);
              Console.WriteLine("Computed area is {0}" + "\n\n" + "Computed Triangle is: {1}"         + "\n", squ.ComputeArea(rec.Area), tri.ComputeArea(rec.Area));
  
          }
      }
  
      abstract class GeometricFigure
      {
          public decimal _height, _width, _area;
  
  
          public decimal Height
          {
              get { return _height; }
              set { _height = value; }
          }
  
          public decimal Width
          {
              get { return _width; }
              set { _width = value; }
          }
  
          public decimal Area
          {
              get { return _area; }
          }
  
          public abstract decimal ComputeArea();
  
      }
  
      class Rectangle : GeometricFigure
      {
          private decimal height, width;
  
          public Rectangle(decimal sideA, decimal sideB)
          {
              this.height = sideA;
              this.width = sideB;
          }
  
          public Rectangle()
          {
          }
  
          public override decimal ComputeArea()
          {
              Console.WriteLine("The Area is" + _width.ToString(), _height.ToString());
              return width * height;
          }
  
      }
  
      class Square : Rectangle
      {
          public Square(decimal sideA, decimal sideB)
          {
              this._width = sideA;
              this._height = sideB;
              if (sideA != sideB)
                  this._height = this._width;
          }
  
          public Square(decimal xy)
          {
              this._width = xy;
              this._height = this._width;
          }
  
          public override decimal ComputeArea(decimal _area)
          { return _area = this._width * this._height; }
      }
  
      class Triangle : GeometricFigure
      {
          public Triangle(int x, int y)
          {
              this.Width = x;
              this.Height = y;
          }
  
          public override decimal ComputeArea(decimal _area)
          { return _area = (this.Width * this.Height) / 2; }
      }
  }
  </code></pre>