1 files changed, 44 insertions, 0 deletions
diff --git a/MindBox.Lib/Triangle.cs b/MindBox.Lib/Triangle.cs
new file mode 100644
index 0000000..54e8a85
--- /dev/null
+++ b/MindBox.Lib/Triangle.cs
@@ -0,0 +1,44 @@
+namespace MindBox.Lib;
+
+public class Triangle : FlatShape
+{
+	private readonly double[] _sides;
+
+	public Triangle(double a, double b, double c)
+	{
+		_sides = new[] { a, b, c };
+		if (_sides.Any(side => side <= 0))
+		{
+			throw new ArgumentException($"Side(s) cannot be non-positive: {string.Join(" ;", _sides.Where(side => side <= 0))}");
+		}
+		if (a >= b + c || b >= c + a || c >= a + b)
+		{
+			throw new ArgumentException($"Sides lengths are not valid: {a}, {b}, {c}");
+		}
+	}
+	public override double GetArea()
+	{
+		if (_area != null)
+		{
+			return _area.Value;
+		}
+		else
+		{
+			double semiPerimeter = _sides.Sum() / 2;
+			_area = Math.Sqrt(semiPerimeter *
+				(semiPerimeter - _sides[0]) *
+				(semiPerimeter - _sides[1]) *
+				(semiPerimeter - _sides[2]));
+			return _area.Value;
+		}
+	}
+	public bool IsRight()
+	{
+		var sorted = _sides.OrderByDescending(x => x);
+
+		double hypotenuse = sorted.First();
+		var catheti = sorted.Skip(1);
+
+		return hypotenuse * hypotenuse == catheti.Sum(x => x * x);
+	}
+}