A hemispherical bowl has its external diameter equal to 10 cm and its thickness is 1 cm. What is the whole surface area of the bowl ? -Maths 9th

A hemispherical bowl has its external diameter equal to 10 cm and its thickness is 1 cm. What is the whole surface area of the bowl ? -Maths 9th
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1 Answer

Answer :

External radius of hemispherical bowl = 5 cm  Internal radius of the bowl = (5 – 1) cm = 4 cm  Surface area of external portion = 2π(5)2 = 50 p sq. cm  Surface area of internal portion = 2π(4)2 = 32 p sq. cm  Area of the top circular portion = π(52 – 42) = 9p sq. cm  ∴ Total surface area of the bowl = 50π + 32π + 9π  = 91π sq. cm = (91×227)(91×227) sq. cm  = 13 × 22 sq. cm = 286 cm2
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