Question:
State in each case whether A ⊂ B or A ⊄ B.
A = {x : x is a triangle in a plane}, B = {x : x is a rectangle in the same plane}
Solution:
A ⊄ B
We have, A = set of triangles and B = set of rectangles
Now, we can see elements of A does not belong to B since the set of rectangles does not include a set of triangles.