Explanation: Constitutional isomers are the isomers having same molecular formula but have different connectivity of groups.
The two cyclic constitutional isomers of trans-1,2-dimethylcyclobutane having same ring size are:trans-1,1-dimethylcyclobutanetrans-1,3-dimethylcyclobutane
These two isomers are shown in the image attached below.
The drawings are in the figure attached below.
"Constitutional isomers" is a term used in chemistry to refer to chemical compounds that have the same constitution and molecular formula distributed in a different structure. That is, the compound has the same atoms, but when built in a three-dimensional image, these atoms occupy different places within the same structure.