Yeah I ask how to find a few clips of two vectors angle?

Asked a small problem, how to find a few that way cocos2dx two vectors in the folder angle?
Such CCPoint a (1, 0), CCPoint b (1, 1); angle with the (0,0) should be 45 degrees.
I think he had a cppAngle (pt1, pt2) function, but the result is not on how it?
Or know how cosine seeking degrees it?

Reply:
The result is in radians, and 3.14 / 4 = 45 degrees