cosine Funktion test

src/test/test_funktionen.c

@@ -143,4 +143,11 @@ void test_sine(void) {
     TEST_ASSERT_EQUAL_FLOAT(0.479426, result);
 }
 
+void test_cosine(void) {
+    float result = cosine(1.0);
+    TEST_ASSERT_EQUAL_FLOAT(0.540302, result);
+    // Add more test cases for different inputs and expected outputs
+}
+
+
 #endif