added test for sin of value between zero and negative pi as well as corresponding functionality

src/main/py/trigonometry.py

@@ -15,6 +15,7 @@ def rad2deg(radNumber):
     return (radNumber * 180) / math.pi
 
 def sin_approx_bhaskara(radNumber):
+
     while(radNumber > 2 * math.pi):
         radNumber -= 2 * math.pi
 
@@ -23,6 +24,10 @@ def sin_approx_bhaskara(radNumber):
         radNumber = subract(math.pi, radNumber)
         shallFlipTheResult = 1
 
+    if 0 > radNumber > -2*math.pi:
+        radNumber *= -1
+        shallFlipTheResult = 1
+
 
     num = multiply(16, radNumber)
     num = multiply(num, subract(radNumber, math.pi))

src/test/py/test_trigonometry.py

@@ -50,6 +50,9 @@ class MyTestCase(unittest.TestCase):
     def test_sin_2point5_pi_should_be_1(self):
         self.assertEqual(sin_approx_bhaskara(2.5*math.pi), 1)
 
+    def test_sin_negative_point5_pi_should_be_negative_1(self):
+        self.assertEqual(sin_approx_bhaskara(-0.5*math.pi), -1)
+
 
 if __name__ == '__main__':
     unittest.main()