Question

this is the question of ncert

Answer 1

SOLUTION:
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

Hope it helped u any ways sorry to tell that i copied it from some other users answer
cause i gtg bye good night