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Perimeter and Area > Exercise 13.4

Exercise 13.4

1. Find the area of the following rhombuses.

(i)

Answer:

Diagonal 1 (d1) = + = cm

Diagonal 2 (d2) = + = cm

Area of rhombus = 12 × ×

Area = 12 × ×

Area = 12 × 40 = cm²

(ii)

Answer:

Diagonal 1 (d1) = + = cm

Diagonal 2 (d2) = + = cm

Area of rhombus = 12 × ×

Area = 12 × ×

Area = 12 × 48 = cm²

2. Find the missing values.

Answer:

Diagonal-1 (d₁)Diagonal-2 (d₂)Area of rhombus
12 cm16 cm cm²
27 mm mm2025 mm²
24 m57.6 m

3. If length of diagonal of a rhombus whose area 216 sq. cm. is 24 cm. Then find the length of second diagonal.

Answer:

Area of rhombus = 12 × d1 × d2

216 = 12 × × d2

216 = × d2

d2 = 216 ÷

d2 = cm

4. The floor of a building consists of 3000 tiles which are rhombus shaped. The diagonals of each of the tiles are 45 cm and 30 cm. Find the total cost of polishing the floor, if cost per m² is ₹ 2.50.

Answer:

Area of one tile = 12 × d1 × d2

Area = 12 × ×

Area = 12 × 1350 = cm²

Total area of 3000 tiles = 3000 ×

Total area = cm²

Convert cm² to m² (1 m² = 10000 cm²):

Total area in m² = 2025000 ÷

Total area in m² =

Cost of polishing per m² = ₹

Total cost of polishing = 202.5 ×

Total cost = ₹