diff --git a/src/test/test_funktionen.c b/src/test/test_funktionen.c
index 3f9817b..67e690f 100644
--- a/src/test/test_funktionen.c
+++ b/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
\ No newline at end of file