Two hemispherical domes are to be painted -Maths 9th

1 Answer

Answer :

Let radii of the bases of two domes be r and R. ∴   2πr = 17.6  ⇒  2 x 22/7 x r = 17.6 ⇒ r = 17.6 x 7/2 x 22 = 2.8 cm and 2 πR = 70.4  ⇒ 2 x 22/7 x R = 70.4 ⇒ R = 70.4 x 7/2 x 22 = 11.2 cm Now, area of two hemispherical domes = 2πr2  + 2πR2 = 2 x 22/7 x 2.8 x 2.8 x 2 x 22/7 x 11.2 x 11.2 = 49.28 + 788.48 cm2  = 837.76 cm2  Cost of painting at the rate of  ₹10 per cm2 = 837.76 x 10  = ₹8377.6

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