public static void Perimeter()
        {
            EquilateralTriangle triangle = new EquilateralTriangle(8);
            double area = triangle.Perimeter();

            Assert.AreEqual(24, area, Tolerance);
        }
        public void EquilateralTriangleTest()
        {
            EquilateralTriangle triangle = new EquilateralTriangle();

            triangle.SideLength = 10;

            double areaExpected = 43.30;
            double area         = Math.Round(triangle.Area(), 2);

            Assert.Equal(areaExpected, area);

            double perimeterExpected = 30;
            double perimeter         = triangle.Perimeter();

            Assert.Equal(perimeterExpected, perimeter);
        }