The curved surface area of the dome = 2π2 × "" × 2.8 × 2.8 m2249.2

1.	The curved surface area of the dome = 2π2 × "" × 2.8 × 2.8 m2249.28 mNow, cost of painting 100 cem2 is Rs 5.Thus, the cost of painting 1 m2- Rs 500Therefore, cost of painting the whole dome= Rs 500 × 49.28= Rs 24640EXERCISE 13.4Assume π, unless stated otheFind the surface area of a sphere of radius:(i) 10.5 cmFind the surface area of a sphere of diameter:(ii) 5.6 cm
Answer» Surface area of sphere = 4 × pi × r² i) 4 × 22/7 × (10.5)² = 88/7 × (10.5)² = 1386 cm² ii) 4 × 22/7 × (5.6)² = 88/7 × (5.6)² = 394.24

The curved surface area of the dome = 2π2 × "" × 2.8 × 2.8 m2249.28 mNow, cost of painting 100 cem2 is Rs 5.Thus, the cost of painting 1 m2- Rs 500Therefore, cost of painting the whole dome= Rs 500 × 49.28= Rs 24640EXERCISE 13.4Assume π, unless stated otheFind the surface area of a sphere of radius:(i) 10.5 cmFind the surface area of a sphere of diameter:(ii) 5.6 cm

Answer»

Surface area of sphere = 4 × pi × r²

i) 4 × 22/7 × (10.5)² = 88/7 × (10.5)²

= 1386 cm²

ii) 4 × 22/7 × (5.6)² = 88/7 × (5.6)²

= 394.24