Angle between two lines in space 
Angle between two planes in space 
Angle between a line and a plane 
The angle t between two lines is the angle between two direction vectors of the lines.
Take line a with direction vector u and line b with direction vector v.
That is:
u.v= u.v.cos(t)
and then:

The angle between two planes is given by the angle between the normal vectors,
n_{1} and n_{2}, that is:

Let's name t to the angle which line makes with plane, v the direction vector of line and n the normal vector of the plane.
Then:
