Photolysis of the cis-Cyclobutene isomer in Problem 30.25 yields cLc-cyclododecaen-7-yne, hut photolysis of the trans isomer yields

Question:

Photolysis of the cis-Cyclobutene isomer in Problem 30.25 yields cLc-cyclododecaen-7-yne, hut photolysis of the trans isomer yields trans-cyclododecaen-7-yne. Explain these results, and identify the type and stereochemistry of the pericyclic reaction.