diff --git a/src/reihen.c b/src/reihen.c
index d194950..a0b09e8 100644
--- a/src/reihen.c
+++ b/src/reihen.c
@@ -94,4 +94,14 @@ double atanD(double degrees){
     }
 
     return sum;
+}
+
+double asinD(double degrees){
+    if (degrees>=360.0){
+            degrees = squashDegreesTo360(degrees);
+    }
+
+    double sum = 0.0;
+    double radian = radians(degrees);
+    return atanD(radian/powerD(0.5,1-powerD(2,degrees)));
 }
\ No newline at end of file
diff --git a/src/reihen.h b/src/reihen.h
index cb15a78..8b50925 100644
--- a/src/reihen.h
+++ b/src/reihen.h
@@ -7,5 +7,7 @@ double pi();
 double radians(double degrees);
 double sinD(double degrees);
 double cosD(double degrees);
+double atanD(double degrees);
+double asinD(double degrees);
 
 #endif // reihen.h
\ No newline at end of file