Triangulation means the measuring of distances in surveys with triangles. If the distance of two objects and the angle between is knwon, the distance between these objects can be calculated.
Given the diagram we have:
So, the distance between both objects will be calculated by:

Where:
Distance to the first object a = 6
Distance to the first object b = 6
Angle between both objects θ = 60°
Substitute the values, we have:

Simplify:

So, the distance between both objects c = 6 inches