Correct Answer - Option 2 : 392 cm

^{2}
**Given:**

ΔMNO ∼ ΔDEF

The sides of ΔMNO and ΔDEF are in the ratio 4 ∶ 7.

Area of (ΔMNO) = 128 cm^{2 }

**Concepts used:**

The ratio of the area of similar triangles is equal to the square of the ratio of sides of corresponding triangles.

**Calculation:**

ΔMNO ∼ ΔDEF

Area (ΔMNO)/Area (ΔDEF) = (Side of ΔMNO/Side of ΔDEF)^{2 }

⇒ 128 cm^{2}/Area (ΔDEF) = (4/7)^{2}

⇒ Area (ΔDEF) = 128 × (49/16) cm^{2 }

⇒ Area(ΔDEF) = 392 cm^{2}.

**∴ Area of ΔDEF is equal to 392 cm**^{2}.