For hh1

using System;

public interface IFigure
{
    double CalculateArea();
}

public class Circle : IFigure
{
    public double Radius { get; }

    public Circle(double radius)
    {
        if (radius <= 0)
        {
            throw new ArgumentException("Радиус должен быть положительным числом.");
        }

        Radius = radius;
    }

    public double CalculateArea()
    {
        return Math.PI * Math.Pow(Radius, 2);
    }
}

public class Triangle : IFigure
{
    public double SideA { get; }
    public double SideB { get; }
    public double SideC { get; }

    public Triangle(double sideA, double sideB, double sideC)
    {
        if (!IsValidTriangle(sideA, sideB, sideC))
        {
            throw new ArgumentException("Невозможно создать треугольник с заданными сторонами.");
        }

        SideA = sideA;
        SideB = sideB;
        SideC = sideC;
    }

    public double CalculateArea()
    {
        double s = (SideA + SideB + SideC) / 2;
        return Math.Sqrt(s * (s - SideA) * (s - SideB) * (s - SideC));
    }

    public bool IsRightTriangle()
    {
        double[] sides = { SideA, SideB, SideC };
        Array.Sort(sides);
        return Math.Pow(sides[0], 2) + Math.Pow(sides[1], 2) == Math.Pow(sides[2], 2);
    }

    private bool IsValidTriangle(double a, double b, double c)
    {
        return a + b > c && a + c > b && b + c > a;
    }
}


using Microsoft.VisualStudio.TestTools.UnitTesting;

[TestClass]
public class FigureTests
{
    [TestMethod]
    public void CircleAreaCalculation()
    {
        Circle circle = new Circle(5);
        double expectedArea = Math.PI * Math.Pow(5, 2);
        Assert.AreEqual(expectedArea, circle.CalculateArea(), 0.0001);
    }

    [TestMethod]
    public void TriangleAreaCalculation()
    {
        Triangle triangle = new Triangle(3, 4, 5);
        double expectedArea = 6;
        Assert.AreEqual(expectedArea, triangle.CalculateArea(), 0.0001);
    }

    [TestMethod]
    public void RightTriangleCheck()
    {
        // Это часть будто не правильно работает…
        Triangle rightTriangle = new Triangle(3, 4, 5);
        Assert.IsTrue(rightTriangle.IsRightTriangle());

        Triangle nonRightTriangle = new Triangle(1, 2, 3);
        Assert.IsFalse(nonRightTriangle.IsRightTriangle());
    }
}