Respuesta :

mergl
cos^-1(4/2)=cos^-1(2)-pi/2
The inverse cosine function has a domain of [-1,1], and -2 is outside of that range, so there is no solution
Unless you meant cos^-1, as in 1/cos or sec, in which case cos(1/2)-pi/2 
This would be pi/3-pi/2=-pi/6