CBSE Notes, Lectures

CBSE - Mathematics - Surface Areas and Volumes

Surface Areas and Volumes

NCERT Exercise Exercise 13.4

A hemispherical bowl is made of steel, 0.25 cm thick. The inner radius of the bowl is 5 cm. Find the outer curved surface area of the bowl.

Inner radius of the bowl (r) = 5 cm
Thickness of the steel = 0.25 cm
∴ outer radius (R) = (r + 0.25) cm
                              = (5 + 0.25) cm  = 5.25 cm
Outer curved surface = 2πR2
                                  = (2 × 22/7 × 5.25 × 5.25) cm2
                                  = 173.25 cm2

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