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Question
As shown in the figure a cubical block of side 7 cm is surmounted by a hemisphere. Find the surface area of the solid.
Solution
Side of a cube (a) = 7 cm
Radius of a hemisphere (r) = `7/2` cm
Surface area of the solid = T.S.A of the cube + C.S.A of the hemisphere – Area of the base of the hemisphere
= `(6 xx 7^2 + 2 xx 22/7 xx (7/2)^2 - 22/7 xx (7/2)^2)"cm"^2`
= `(294 + 77 - 77/2)"cm"^2`
= `(294 + 77/2)"cm"^2`
= 332.5 cm2
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