public void Cos_Constant()
        {
            PolynomialTerm term = 0;

            PolynomialTerm.Cos(term).AssertIsEqualTo(1);
        }
 public void Cos_Variable()
 {
     PolynomialTerm.Cos(Term.a).AssertIsEqualTo(IndeterminateExpression.Cos('a'));
 }