Question

a cuboidal block of side 5 cm is surmounded by a hemisphere of diameter 4.2 cm find the tsa of the block​

Answer 1

Answer:

hope it would be helpful for u

The decorative block is a combination of a cube and the hemisphere.

For cubical portion:

Each edge= 5 cm

For hemispherical portion:

Diameter= 4.2 cm

Radius(r)= 4.2/2= 2.1 cm

Total surface area of the cube= 6 × (edge)²

= 6 (5)²= 6 × 25= 150 cm²

Here the part of the cube where the hemisphere is attached is not included in the surface area.

So the total surface area of the decorative block= total surface area of the cube+ area of base of hemisphere + curved surface area of hemisphere

total surface area of the decorative block= 150 - πr² + 2πr²

= 150 +πr²

= 150 + (22/7) × 2.1× 2.1

= 150 + 13.86 = 163.86cm²

Hence,total surface area of the decorative block=163.86 cm²