8. Let (X, d) be a metric space, and A, B are subset of X, then (i) Fr(A) = A n (A)° = Ã – int A A - int A %D (ii) Fr(A) = 0 if and only if A is both open and closed %3D (iii) A is closed if and only...

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Extracted text: 8. Let (X, d) be a metric space, and A, B are subset of X, then (i) Fr(A) = A n (A)° = Ã – int A A - int A %D (ii) Fr(A) = 0 if and only if A is both open and closed %3D (iii) A is closed if and only if A Fr(A) ini (A mi) (iv) A is open if and only if A° 2 Fr(A) (v) Fr(AnB) C Fr(A) U Fr(B). The equality holds if A N B = ¢ (vi) Fr(int A) C Fr(A). %3D bas amonoori mort wollo