Question

A 2-kilogram box hangs by a massless rope from a
ceiling as shown. A force slowly pulls the box horizontally to
the side until the force is equal to 10 N. The box is then in
equilibrium. The angle that the rope makes with the vertical
is closest to:

http://2.bp.blogspot.com/-fEj7d6BMz5Q/Tlg9jogs2QI/AAAAAAAAAFk/HS5_yC2TDPQ/s1600/BoxInEqm.png

(a) sin-1(0.5)
(b) tan-1(2.0)
(c) sin-1(2.0)
(d) 45o
(e) tan-1(0.5)