Question

the internal and external diameter of a hollow hemispherical vessel are 21 cm 28 CM respectively find 1. internal Curved surface area, 2 external Curved surface area, 3. total surface area, 4. volume of material of the vessel

Answer 1

internal diameter=21cm
internal radius=21/2=10.5cm
external diameter=25.2cm
external radius=25.2/2 =12.6cm
surface area of internal bowl=2πr²
=2(22/7)(10.5²)
=2×22×10.5×10.5/7
=693cm²
surface area of external bowl=2πR²
=2(22/7)(12.6²)
=2×22×12.6×12.6/7
=997.9cm²
surface area of ring=π(R²-r²)
=22/7(12.6²-10.5²)
=22/7(48.51)
=22×48.51/7
=152.46cm²
cost of internal bowl=693×0.1=69.3
cost of external bowl=997.9×0.1=99.79
cost of ring=152.46×0.1=15.246
cost of bowl=69.3+99.7+15.2=184.2

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