I want an image to appear in one of several pre-mediated positions. (positions that are an equal distance from a place of focus)

So I want to place the image in a random place, amongst a selection.

however, 'loc' requires that x and y coordinates are entered seperately.
I tried using the rand function for a selection of x,y values, looking like this:

loc:
rand((x,y),(x2,y2),(x3,y3)),1

But that did not work.

Will I have to make a different stimulus for every different position, and then randomly cycle through the stimuli? considering that multiple combinations of images must appear on each trial, this is looking impractical?

surely there is a way to place objects in a random position out of a selection? It says that the rand() function can be used to place objects in random places, but there is no other information available on this topic?