public void TestGetCosTheta()
        {
            var testSubject00 = new LinearEquation(-1, 2);
            var testSubject01 = new LinearEquation(1, 3);

            var testResult = testSubject00.GetCosTheta(testSubject01);

            Console.WriteLine(testResult);
            Assert.IsTrue(0.707106781 - testResult < 0.000001);
        }