Question

write the expression for the total surface area of a solid hemisphere of radius ‘r’​

Answer 1

Answer:

3πr2  square units

Step-by-step explanation:

We know that the area of a circle with radius r units is πr2 square units.

So, the area of circular base of radius r units =πr2

Now, the total surface area of the solid hemisphere =2πr2+πr2

Taking πr2 common from both the terms, we get,

=πr2(2+1)

Simplifying the expression, we get,

=3πr2

So, the total surface area of a solid hemisphere of radius r units is 3πr2 square units.

Answer 2

Answer:

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The surface area of a solid hemisphere with radius r is

Medium

Solution

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Correct option is C)

Surface area of a solid sphere with radius r is 4πr

2

A solid sphere can be divided into two equal hemispheres with a flat surface and a curved surface.

Curved surface area of a solid hemisphere will be half the surface area of solid sphere.

Hence, curved surface area of solid hemisphere =

2

1

∗4πr

2

=2πr

2

And, flat surface area of hemisphere will be the area of circle with radius r.

Hence, flat surface area of hemisphere =πr

2

Total surface area of a solid hemisphere with radius r is, S=2πr

2

+πr

2

=3πr

2