Question

The surface area of ​​a 21 cm diameter sphere is known​

Answer 1

Answer:

diameter (d)= 21cm

radius (r) = 21/2 cm

solution:

surface area of a sphere = 4*pie*r ^2

=4*22/7*21/2*21/2

=66*21

=1386cm ^2.

Answer 2

Answer:

1386cm^2

Step-by-step explanation:

diameter (d)=21cm

radius(r)=21/2cm

surface area of sphere=4πr^2

=4×22/7×21/2×21/2

=1386cm^2