how to create a clipping mask to a complex pattern

[James21953383fnof]

Im trying to clip this triangular pattern so that the photo behind it is shown in each individual triangle shape, please see pic attached

[John Mensinger]

Select all the tirangles and make them a Compound Path (Object > Compound Path > Make).

Add the image to the selection, and choose Object > Clipping Mask > Make.

[Anna Lander]

in addition to John's message: make sure that there are gaps between the triangles, otherwise, they will look like a solid shape.

[Ton Frederiks]

If I understand correctly:

Make a copy of the triangles.

Select all the triangles and unite them in the pathfinder.

Use the result as clipping mask.

Paste the copy in front, fill with none and give it a stroke.