Question

2. A cube whose edge is 21 cm long has a circle
of diameter 21 cm on each of its faces painted
black. What is the total area of the unpainted
surface of the cube?​

Answer 1

Total unpainted area=TSA of cube - 6( area of circle)

=> 6(s)^2-6(πr^2)

s=21 and r=10.5

Total unpainted area=2,646-2077.11

=568.89 cm^2

Answer 2

Remaining area= Area of square- Area of circle

= s2-Pie r2

= 21^2- 22/7 *21/2*21/2

=441- 33*21/2

= 441-693/2

= 882-693/2

= 289/2

= 94.5 cm2

Therefore, Area unpainted= 6s2

=6*94.5

=567cm2