Question

4. A cubical block of side 7 cm is surmounted by a hemisphere. What is the greater
diameter the hemisphere can have? Find the surface area of the solid.
​

Answer 1

Answer:

The greatest diameter=side of the cube=7cm.

The radius of the hemisphere =3.5cm.

Now,

The Surface Area of Solid=Surface Area of Cube - Surface Area of Base Hemisphere + Curve Surface Area of Hemisphere

Surface Area of Cube

=6×side 2

=6×7×7

=294sq cm

Surface Area of Base of Hemisphere is,

=πr 2

= 7 22 ×3.5 2

=38.5cm 2

Curved Surface Area of Hemisphere is,

=2×38.5

=77sq cm

∴ total Surface Area is =294−38.5+77

=332.5sq cm.