Given: One diagonal of a rhombus is 25% more than the other diagonal. The area of the rhombus is 40 cm2. Formula used: Area of the rhombus = (1/2) × d1 × d2 Area of circle = π d2/4 Calculations: Let d be the smaller diagonal, then the longer diagonal will be 1.25d. Area of the rhombus = (1/2) × d1 × d2 ⇒ (1/2) × d × 1.25d = 0.625d2 ⇒ 0.625d2 = 40 ⇒ d = 8 cm The longer diagonal will be the diameter of the circle, Area of circle = (π (1.25d)2)/4 ⇒ 100π/4 = 25π cm2 Additional Information Rhombus is special types of parallelogram in which all sides are equal. Area of rhombus = 0.5 × (product of the lengths of the diagonals) Area of rhombus = (side length of a rhombus)2 × sin of any interior angle.