diff --git a/test/test_trigonometricFunctions.c b/test/test_trigonometricFunctions.c
index 04c55df..45e1328 100644
--- a/test/test_trigonometricFunctions.c
+++ b/test/test_trigonometricFunctions.c
@@ -15,3 +15,9 @@ void test_trigonometricFunctions_trigonometricFunctionsofsin(void) {
     result = calculate_sin_double(45);
     TEST_ASSERT_DOUBLE_WITHIN(0.1, expectedResult, *result);
 }
+void test_trigonometricFunctions_trigonometricFunctionsofcos(void) {
+    double expectedResult = 0.525321989 ;
+    double *result;
+    result = calculate_cos_double(45);
+    TEST_ASSERT_DOUBLE_WITHIN(0.1, expectedResult, *result);
+}
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