diff --git a/src/c/funktionen.h b/src/c/funktionen.h
index 40067b4..ae99a8c 100644
--- a/src/c/funktionen.h
+++ b/src/c/funktionen.h
@@ -38,5 +38,8 @@ int characterAppearanceInString(char c, char string[]);
 // Function to calculate the sine of an angle in radians
 float sine(float x);
 
+// Function to calculate the cosine of an angle in radians
+float cosine(float x);
+
 
 #endif
\ No newline at end of file