Combine and Appened to array

byte[] arr1 = new byte[] {1,2,3,4,5};
byte[] arr2 = new byte[] {6,7,8};
public static T[] Combine<T>(T[] original, T[] additions)
{
    var arr = new T[original.Length+additions.Length];
    original.CopyTo(arr,0);
    additions.CopyTo(arr,original.Length);
    return arr;
}

public static void Appened<T>(ref T[] original, T[] additions)
{
    int length = original.Length;
    Array.Resize(ref original, original.Length + additions.Length);
    Array.Copy(additions, 0, original, length, additions.Length);
}