Mathematics for IGCSE & O level - Sets (Section 1 - No. 10)
What can be said about two sets if their union equals one of the sets?
They are disjoint.
One is a subset of the other.
They are identical.
They have the same number of elements.
स्पष्टीकरण
If A ∪ B = A, then B is a subset of A.