What universal set (s) would you propose for each of the following

What universal set (s) would you propose for each of the following:
(i) The set of right triangles
(ii) The set of isosceles triangles
Answer
(i) Right triangles is a specific type of a triangle so that the universal set can be the set of triangles.
(ii) Isosceles triangles is a specific type of a triangle so that the universal set can be the set of triangles