How to convert a Matrix4 or Quaternion to angle in degrees

I'm asking if anyone could help me in converting a Matrix4 or Quaternion to angle in degrees, I'm working on Kinect windows SDK 1.5 using C#, the sdk 1.5 provides the joint orientation but only in Matrix4 or Quaternion and i need the angles in degrees.

Solution

Well, the numbers in quaternions and matrix4 are cosines. Therefore, the following functions solves it:

Function cs_a_gr(cose)
    Return 180 / PI * Acos(cose)
End Function