diff --git a/AngouriMath/Convenience/MathS.cs b/AngouriMath/Convenience/MathS.cs
index 23414bd5f..9bdc89bc4 100644
--- a/AngouriMath/Convenience/MathS.cs
+++ b/AngouriMath/Convenience/MathS.cs
@@ -198,9 +198,27 @@ public static EntitySet Solve(Entity equation, VariableEntity var)
         /// </summary>
         /// <param name="a"></param>
         /// <returns>
-        /// angle between B and C
+        /// angle between B and A
         /// </returns>
         public static Entity Arccotan(Entity a) => Arccotanf.Hang(a);
+     
+        /// <summary>
+        /// https://en.wikipedia.org/wiki/Inverse_trigonometric_functions
+        /// </summary>
+        /// <param name="a"></param>
+        /// <returns>
+        /// angle between C and B
+        /// </returns>
+        public static Entity Arcsec(Entity a) => Arccosf.Hang(1 / a);
+     
+        /// <summary>
+        /// https://en.wikipedia.org/wiki/Inverse_trigonometric_functions
+        /// </summary>
+        /// <param name="a"></param>
+        /// <returns>
+        /// angle between C and A
+        /// </returns>
+        public static Entity Arccosec(Entity a) => Arcsinf.Hang(1 / a);
 
         /// <summary>
         /// https://en.wikipedia.org/wiki/Natural_logarithm
@@ -414,4 +432,4 @@ public static Entity OptimizeTree(Entity tree)
             return tree;
         }
     }
-}
\ No newline at end of file
+}
diff --git a/AngouriMath/Convenience/SynonymFunctions.cs b/AngouriMath/Convenience/SynonymFunctions.cs
index e6261419c..d31b4eb01 100644
--- a/AngouriMath/Convenience/SynonymFunctions.cs
+++ b/AngouriMath/Convenience/SynonymFunctions.cs
@@ -36,6 +36,8 @@ internal static class SynonymFunctions
             { "lnf", args => MathS.Log(args[0], MathS.e) },
             { "secf", args => MathS.Sec(args[0]) },
             { "cosecf", args => MathS.Cosec(args[0]) },
+            { "arcsecf", args => MathS.Arcsec(args[0]) },
+            { "arccosecf", args => MathS.Arccosec(args[0]) },
         };
 
         /// <summary>
diff --git a/AngouriMath/Core/FromString/SyntaxInfo.cs b/AngouriMath/Core/FromString/SyntaxInfo.cs
index d2453b558..cbe4ebd33 100644
--- a/AngouriMath/Core/FromString/SyntaxInfo.cs
+++ b/AngouriMath/Core/FromString/SyntaxInfo.cs
@@ -42,6 +42,8 @@ internal static class SyntaxInfo
             { "arccos", 1 },
             { "arctan", 1 },
             { "arccotan", 1 },
+            { "arcsec", 1 },
+            { "arccosec", 1 },
         };
         internal static readonly Dictionary<char, string> operatorNames = new Dictionary<char, string>
         {