C# pytanie

namespace Lab1
{
    class RightTriangle
    {

        private double a, b;

        public double A
        {
            get { return a; }
            set
            {
                if (value > 0) a = value;
            }
        }
        public double B
        {
            get { return b; }
            set
            {
                if (value > 0) b = value;
            }
        }

        private double ComputeC()
        {
            //return Math.Sqrt(a * a + b * b);     //which is correct?
            //return Math.Sqrt(A * A + B * B);
        }

        public double ComputeSine()
        {
            return ComputeC() / a;
        }

    }
}