A solid hemisphere has a radius of 7 cm. Find the total surface area.
400 cm2
462 cm2
66 cm2
308 cm2
Explanation
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Discussions (10)

Here is the correct explanation:
surface area of a hemisphere = 3πr2
π 22 while r = 7
solution=3 * π(22/7) * 49
461.8= 462

the total surface area of a hemisphere = 3 * pi * radius * radius
hencethe total surface area of a hemisphere of radius 7 cm
= 3 * ( 22 / 7 ) * 7 * 7
= 3 * 22 * 7
= 21 * 22
= 462 cm sq

The selected answer is wrong:
Curved surface area is 2πr^2 but total surface area is curved surface area + area of the top which is 2πr^2 + πr^2 = 3πr^2
Hence, here, the solution is 3*π*7^2 = 462cm^2
Curved surface area was solved for here

TSA of an hemisphere=2nr + nr^2 =3nr^2
:- 3*22/7*7^2=461.814
so correct ans is B not D.




