Four positions of a cube are shown below. Which symbol is opposite the face having "Δ"?

We follow the given pattern :-
The six symbols on the six faces of the given cube are: Ο, Δ, +, –, × and ÷. From figure 1,2 and 4, ÷, ×, – and + can not be opposite to circle.
Hence, from the four positions of the cube it is clear that the circle lies opposite triangle.