Question

A hemispherical dome of a buildimg needs to be painted.If the circukference of the base of dime is 17.6cm,fomd the cost of painting it,it given the cost of rs 5 per 100 cm^2

Answer 1

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Let the radius of base of the dome = r

circumference of base of dome = 17.6 m

⇒2πr = 17.6
⇒2×227×r = 17.6
⇒r = 17.6 × 744
⇒r = 2.8 m

CSA of hemispherical dome 

= 2πr2   
 = 2×227×(2.8)2 
= 49.28 m2

cost of painting 1 m2 area of dome 

= Rs 5
Cost of painting 
= Rs (100×5) 
= Rs 500

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